Monthly Archives: June 2013

Accessing Scientific Journal Articles

For attorneys trying to access scientific journal articles related to the forensic evidence in their cases, purchasing these articles online can be cost-prohibitive at around $30 per article. If someone in your office has an affiliation with a university, such as an intern, paralegal, or assistant who is pursuing another degree, they may be able to access the articles you need through their university.

However, if you don’t have any affiliation with a university, a great way to access these scientific journal articles is by getting a Borrower’s Card from a library in the UNC system. For $25 per year, a North Carolina resident can get a Borrower’s Card which will allow access to databases of free full text academic articles while at the library. Unfortunately, the borrower can only access the articles from the library, but PDFs of the articles can be saved on a jump drive, emailed, or printed for later use.

More information about the Borrower’s Card is available here.

Another way to access journal articles is through the public library system. If you are a North Carolina resident and have a public library card, simply go to NCLive which offers access to a variety of academic journals, news articles, and scientific articles for at-home use (for free!). In many cases, the full-text document can be printed, emailed, or saved on your computer. There are various databases which can be searched. Attorneys may be interested in these databases: Academic Search Complete, ArticleFirst, Health Source: Nursing/Academic, Newspaper Source Plus and Science Reference Center. However, fewer articles are available through NCLive than through the UNC system.

Leave a comment

Filed under Resources, Uncategorized

Techniques for Collecting and Analyzing Fingerprints

Fingerprint evidence left behind by a suspect or victim may identify who was at a crime scene and what he or she touched. However, it is important for defense attorneys to know, and to inform the jury, that the techniques used to locate and identify fingerprints are far from a perfect science. An understanding of how fingerprints are located and lifted can help attorneys recognize if a flawed analysis was performed by investigators or lab technicians. Further, knowledge of the various fingerprint collection techniques is essential to successful cross-examination of crime scene technicians and fingerprint examiners. This post attempts to provide an overview of the techniques used to locate, lift, and identify a fingerprint.

Step 1: Locating the fingerprint

Locating a fingerprint often requires a vigilant and calculated search. However, in circumstances where the print is visible to the naked eye, finding a fingerprint is relatively easy. The more intricate searches take place when the print is present on a surface but not visible. The type of fingerprint left behind usually determines the amount of time and effort investigators must put into locating the print.

According to Forensic Science, there are three types of fingerprints. D.P. Lyle, Forensic Science (ABA Fundamentals), p. 255 (2012):

  • Patent prints are easy to locate since they are visible to the naked eye. Patent prints occur when someone has a substance on their fingers such as grease, paint, blood, or ink that leaves a visible print on a surface.
  • Plastic prints are also easy to locate but are less common than patent prints since they occur when someone touches an object such as wax, butter, or soap and leaves a three-dimensional impression of the finger on the object.
  • Latent prints are the most common type of print and take the most effort to locate since they are invisible. Latent prints occur when someone touches any porous or nonporous surface. The natural oils and residue on fingers leave a deposit on surfaces which mirror the ridges and furrows that are present on the individual’s finger.

Investigators often follow a two-phase process when searching for fingerprints. The first phase involves looking for patent and plastic prints since they are visible. Often times, a flashlight is used during this phase. The second phase involves a blind search for latent prints, according to Scientific Evidence. Paul C. Giannelli, Edward J. Imwinkelried, Andrea Roth, and Jane Campbell Moriarty, Scientific Evidence, p. 949 § 16.03 (5th ed. 2012). To narrow the search, investigators usually focus on the entry and exits points that the suspect used and any items that appear to have been disturbed, such as overturned lamps or possible weapons. Id.

The type of surface being searched for fingerprints often determines the technique employed by investigators. Id. at 950.

Nonporous Surfaces:

A powder technique is usually used to identify latent prints on nonporous surfaces such as glass, marble, metal, plastic, and finished wood. Id. When powder is distributed on the surface, it adheres to the residue deposited from the finger’s touch, allowing investigators to find the print. Often times, to avoid smudging the print, a magnetic powder technique is used in which the powder is poured on the surface and then spread evenly over the surface using a magnetic force instead of spreading the powder with a brush. See Forensic Science by D.P Lyle p. 256. The color of the powder should contrast with the surface that is being searched to allow better visibility. For example, the investigator should use a white or grey powder if searching a black marble countertop for prints. See Scientific Evidence by Paul C. Giannelli p. 950.

Attorneys should find out whether the crime scene technician who collected prints using fingerprint powder used a disposable brush. If a brush is reused in different locations at a crime scene or reused at another crime scene, the brush can transfer trace amounts of DNA evidence.

Another popular technique for fingerprint location and identification used by both lab technicians and investigators at the crime scene is superglue fuming. Superglue fuming is a chemical process that exposes and fixes fingerprints on a nonporous surface. Id. at 959. In the lab, the process works by using an airtight tank, known as a fuming chamber, to heat up superglue (liquid cyanoacrylate) which releases gases that adhere to the oily residue of print, thereby creating an image of the fingerprint, according to this article. Superglue fuming can also be performed at the crime scene. Rather than using a fuming chamber, crime scene investigators may use a handheld wand that heats up superglue and a florescent dye, according to Forensic Science by D.P Lyle p. 256. Superglue fuming performed at the crime scene can be vital to preserve prints on items that are being sent to the lab via mail. One of the drawbacks is that if the evidence is fumed too long, it can distort the print, rendering it useless, according to this article. To read the procedure used by North Carolina State Crime Lab to conduct superglue fuming in a fuming chamber, click here. To read the procedure used by the North Carolina State Crime Lab to conduct superglue fuming using a portable wand, click here.

Porous Surfaces:

The powder technique is not as effective on porous surfaces such as fabric, unfinished wood, and paper. Instead, investigators often use chemical methods to locate the print such as iodine fuming, silver nitrate, or ninhydrin. When one of these chemicals comes into contact with the chemicals present in the fingerprint residue (natural oils, fats), the print become visual. See Scientific Evidence by Paul C. Giannelli p. 951-53.

Iodine fuming takes place in a fuming chamber. The process works by heating up solid crystal iodine which creates vapors that adhere to the oily residue of print, producing a brown colored print, according to Forensic Science by D.P Lyle p. 257. One of the drawbacks of using iodine fuming is that the print fades quickly after the fuming takes place and therefore must be photographed quickly. Alternatively, if the print is sprayed with a starch and water solution, it can be preserved for several weeks. Id.

Silver nitrate, when exposed to latent prints, reacts with the chloride of the salt molecules found in print residue, forming silver chloride. When exposed to ultraviolet light, silver chloride turns black or brown, making the print visible. Id. This method works particularly well on impressions left in cardboard and paper-like surfaces, according to Scientific Evidence by Paul C. Giannelli p. 952.

Ninhydrin is more commonly used than iodine fuming and silver nitrate techniques to locate a latent print. Id. The object on which the print is located can be dipped in or sprayed with a ninhydrin solution, which reacts with the oils in the print’s residue to create a bluish print. Forensic Science by D.P Lyle p. 257. One of the drawbacks of using ninhydrin is that the reaction is very slow, often taking several hours for the print to become visible. Id. To accelerate the reaction, the object containing the print can be heated to 80 to 100 degrees Fahrenheit. Id. To read the North Carolina State Crime Lab’s procedures for ninhydrin, click here and here.

A variety of other techniques are sometimes used. For example, laser illumination creates a contrast between the print and the surface which exposes the print. To learn more, see Scientific Evidence by Paul C. Giannelli p. 955-58.

Human Skin:

Locating and identifying fingerprints left on human skin is incredibly difficult. According to Scientific Evidence, the first major obstacle is finding the print since the oily residue left by fingers that creates the fingerprint itself is often present on human skin, making it difficult to create a contrast between the surface (skin) and the print. Further, after a print is left on human skin, the oily residue often disperses and is absorbed into the skin, blurring the print. Two hours is the maximum amount of time that a print on skin may be viable. See Feldman, Meloan, & Lambert, A New Method for Recovering Latent Fingerprints from Skin, 27 J. Forensic Sci. 806 (1982). For more information about current techniques used to identify fingerprints on human skin, see Scientific Evidence by Paul C. Giannelli p. 961-64.

Textured Surfaces:

Surfaces that are not flat or have a rough surface, such as a painting with brush strokes or a golf ball will make the process of identifying and collecting fingerprints more difficult, but not impossible. Click here to read about fingerprints collected from golf balls and other difficult surfaces.

Step 2: Photographing the fingerprint

After the print is located, it is vital that it is photographed before it is lifted. A photograph captures where the print was located in comparison to other objects and captures the orientation of the print. Further, a photograph can serve as a key piece of identification of a patent or plastic print and can be used to compare and possibly match the print to its source. Photographing the print’s location at the crime scene also guards against tampering of evidence. See Scientific Evidence by Paul C. Giannelli p. 964-65.

Step 3: Lifting the fingerprint

“Lifting a fingerprint” means to make a permanent impression of the fingerprint. Lifting a print can be accomplished on either flat surfaces or round surfaces. Lifting a print usually involves a rubber tape with an adhesive surface which is applied to the fingerprint, leaving an imprint on the tape. Often times, a flat object, such as a ruler, will be slowly swiped across the top of the tape to ensure that there are no bubbles or ripples in the tape that will affect the imprint. Next, the tape is carefully peeled off the surface and a plastic cover is placed on the adhesive side of the tape to prevent disruption of the print. Identification information and a description of the location of the print should be written on the back of the tape or card. Id. at 967-68.

After the print is lifted, it is converted into digital data that can be modified to create a clearer image.

Step 4: Comparing the fingerprint

The final step involves a close examination of the characteristics of the fingerprints. For more information about the system of friction ridge classification, click here to read chapter 5 in The Fingerprint Sourcebook by Scientific Working Group on Friction Ridge Analysis, Study and Technology (SWGFAST).

The fingerprint examination process utilizes the ACE-V method which stands for Analysis, Comparison, Evaluation and Verification to compare a print collected from a crime scene to a set of known prints. For a detailed description of the ACE-V method and how it is applied, click here to read chapter 9 of The Fingerprint Sourcebook. This post will not address critiques of the ACE-V method, but additional information that can be used to challenge this technique in court can be found here.

A system called the Automated Fingerprint Identification System (AFIS) was created to find a match to the print using a computer database. To learn more about the AFIS, click here to read chapter 6 of The Fingerprint Sourcebook.

For more information on the lab procedures employed by the North Carolina State Crime Lab in fingerprint collection and analysis, click here.


Filed under Fingerprints

Can Non-Testifying Defense Experts Be Subpoenaed by the State?

As defense attorneys prepare for trial they frequently reach out to experts to determine the strengths and weaknesses of their client’s case and to gain a better understanding of the evidence. In fact, proper preparation for a trial often demands that an attorney assemble information by speaking with experts in an effort to comprehend the complex forensic, medical, or other scientific evidence involved in the case. Experts can be useful tools during the early stages of trial preparation to develop a trial strategy and are often relied upon by defense attorneys at trial to rebut the State’s evidence. In instances where a particular expert’s findings may actually harm the defendant’s case, the defense attorney may choose to not call that expert to testify.

Under the North Carolina discovery statutes, defense attorneys do not have to disclose to the State which experts they consult or hire unless they intend to call the expert to testify at trial. N.C. Gen. Stat. § 15A-905. However, when the defense intends to call an expert to testify, that expert’s report must be made available to the State through pre-trial discovery and the expert will be subject to cross-examination by the State, if called to testify by the defense.

The issue of whether to allow the State to subpoena non-testifying defense experts was decided in State v. Dunn, 154 N.C. App. 1 (2002). In Dunn the defense retained experts to conduct independent lab tests on a suspected controlled substance found in the defendant’s possession but ultimately did not introduce the results of the tests or call the experts to testify. Instead, the State compelled the experts previously retained by the defense to testify to their findings on the State’s behalf. The Court of Appeals ordered a new trial on the grounds that the trial court erred in allowing the State to compel testimony from experts hired by the defense. In doing so, the Court of Appeals stated that “the trial court infringed upon the defendant’s Sixth Amendment right to effective assistance of counsel, and unnecessarily breached the work-product privilege.” Id. at 17.

Sixth Amendment Right to Effective Assistance of Counsel

If the State could subpoena non-testifying defense experts, the Sixth Amendment guarantee of the right to effective assistance of counsel would be severely impaired. Undeniably, consulting with experts is critical to an attorney’s ability to be effective counsel. As noted in State v. Dunn, to be effective counsel, an attorney must enjoy a certain degree of privacy when preparing for a case. Attorneys must be able to consult with experts to gather information, determine the relevant facts, and prepare a case theory without the concern of these experts testifying on their opponent’s behalf. If defense attorneys were aware that the experts they hire could be subpoenaed by the State, attorneys could be less likely to disclose information that is harmful to their client’s case. An atmosphere in which defense attorneys are apprehensive about sharing crucial but incriminating information with their experts can be detrimental because experts will be operating based on incomplete facts and data. This practice could foster a system in which experts reach false or partially false opinions due to incomplete data.

Furthermore, if the State were allowed to subpoena non-testifying defense experts, this could be devastating to defense attorneys’ ability to effectively prepare for trial. Defense attorneys would be forced to choose between consulting with experts to obtain a complete and unbiased assessment of the State’s evidence on one hand, and the fear of creating a potential government witness on the other. As expressed in State v. Dunn, the concern is that defense attorneys may avoid hiring certain experts that do not substantially contribute to their client’s case. Or defense attorneys may be motivated to only hire experts they believe are likely to lean their way.

Work-Product Protection

The work-product doctrine, codified in N.C. Gen. Stat. §§ 15A-904-906, protects the material prepared in anticipation of trial, including the reports and potential testimony of non-testifying experts, from discovery by opposing counsel. Through its application, the doctrine also serves to increase the amount of evidence heard by the jury by allowing defense attorneys to do their own investigative research beyond what was obtained by the State during discovery.

However, the Court of Appeals notes limitations in the work-product doctrine in State v. Dunn, labeling it as a “qualified privilege, not an absolute one” in which the State can discover non-testifying experts’ reports and compel testimony if it can show a special need for the testimony of the defendant’s expert and the defendant’s Sixth Amendment right to effective assistance of counsel is not overrun. Id. at 15.

Attorneys should be aware, however, that experts may not enjoy the same level of protection at sentencing, given the relaxed rules of evidence in sentencing hearings.  In State v. Warren, 347 NC 309 (1997), the North Carolina Supreme Court permitted the State to compel discovery of the defendant’s non-testifying expert’s report on the defendant’s prior bad acts for use in a capital sentencing hearing. The Supreme Court held that “even when the statutes limit the trial court’s authority to compel pretrial discovery, the court may retain inherent authority to compel discovery of the same documents at a later stage in the proceedings.” Id. at 325.

In conclusion, allowing the State to subpoena at trial the non-testifying experts hired by the defense would be devastating to defense teams. Defense attorneys should be aware of State v. Dunn and prepared to object on Sixth Amendment and work-product privilege grounds if the State does attempt to subpoena a defense expert to testify. Defense attorneys should also discuss this restriction with the experts they hire to avoid problems in instances where that expert is not called to testify by the defense and is contacted instead by the State.

Leave a comment

Filed under Experts

Reports of Problems with Polygraph Test

A recent piece of investigative journalism by Marisa Taylor of McClatchy Newspapers has created even more skepticism about the already scientifically-questionable polygraph test. Although polygraph test results are not admissible as evidence in most U.S. courts, the results of a polygraph test play a major role in the police investigation, often times helping the police to obtain confessions and either rule out or target potential suspects. In addition, polygraph exams are frequently used by defense teams, required as part of sex offender treatment and probation programs, and used as part of job application processes.

The article specifically criticizes the LX4000 model which is manufactured by Lafayette Instrument Company, as having a “glitch” that can mean the difference between passing and failing the lie detector. Ten federal agencies, 27 states, including North Carolina, and many local police departments currently use or have relied on the LX4000 to test whether tens of thousands of people are being truthful.

The North Carolina State Bureau of Investigation uses both the LX4000 and LX5000 polygraph models. It is likely that many agencies rely on the LX4000 because the newer model, the LX5000, is more expensive, ranging from $3,200 to $9,500. However, there are still questions that remain unanswered about the accuracy of the newer LX5000 model since the manufacturer, Lafayette, admitted that the new model has the same “potential” as the LX4000 for having troubling issues, according to McClatchy.

The “glitch” identified in the LX4000 relates to the measurement of the amount of perspiration being released by the person taking the polygraph test which is one factor that can indicate his or her level of truthfulness. The LX4000 can measure sweat either in manual mode or automatic mode. The manual mode directly measures the amount of sweat being secreted from the sweat glands. In contrast, automatic mode electronically filters the measurements of sweat, making the data more uniform and easier to interpret. Ideally, the results of the examination would be the same regardless of which mode were used. However, when switching between modes, an alarming 16-point difference has been noted by one veteran federal polygrapher, according to McClatchy. The reason 16 points is such a significant number is that, as Taylor notes, “one point can make a difference” in a polygraph test. Thus, in some circumstances, a person can be classified as a liar or a truth-teller depending on which mode is used.

The results of the LX4000 tend to be less accurate when the automatic mode is used, which is more commonly used by polygraph examiners since it is easier to use and produces more consistent results.

Even more alarming, it is reported that the manufacturing company has been aware of the problem for years. However, the glitch was apparently not shared openly as many polygraph examiners stated in Taylor’s article that they had no idea that their measurements can vary based on which mode they used. Further, since polygraph machines and their operators are not required to pass any certification tests, their potential for inaccurate results are higher than most other forensic equipment which is required to meet certain standards to ensure accuracy.

In response to the attack on its product, Lafayette Instrument Company released a statement two days after Taylor’s article was published. Lafayette assured its customers and colleagues that “there is nothing wrong with the LX4000” and that the LX4000 and LX5000 remain the “best technology available.” Lafayette also maintained that the article was based on “misinformation” and criticized it for alarming people and being misleading. In its response, Lafayette provided a link to the complete set of questions asked by Taylor and the company’s responses. Follow the link to read the correspondence between Taylor and Lafayette manufacturing during Taylor’s investigation in which Lafayette informs Taylor that her information is inaccurate and advises her to verify her sources.

Lafayette maintains that both the manual and automatic modes “have been shown to work satisfactorily.” Lafayette states that no single test item can produce reliable results without analyzing the remainder of the testing data. Perhaps most notably, when posed the question of how often the differences in results occur when manual mode is used instead of automatic mode, Lafayette responds that more research has to be done and it would be “irresponsible to attempt to guess.” However, Lafayette admits that while the results obtained from the two different modes are “in agreement most of the time,” there are “occasional differences,” according to Lafayette’s response.

In sum, attorneys should be aware that there is a potential problem with this particular machine. Many polygraph examiners are aware of this issue and will either use the manual mode of the Lafayette machine or another machine. This problem does not mean that attorneys should discontinue use of private polygraph examinations, but they should discuss this issue with the examiner prior to the exam.

Leave a comment

Filed under Uncategorized