forensics issues in serial murders

The forensic sciences have played a key role in criminal investigations for many years. Recently, there has been increased attention on the forensic sciences by law enforcement, prosecutors, and the general public. Particularly in high profile cases, intense media coverage concerning evidence issues and the work of crime laboratories has served to heighten this interest.

In the past two decades, there have been tremendous technological advances in the laboratory testing of forensic samples. There have also been a number of improvements in the identification and collection of evidence at the crime scene, through innovative processing and evidence collection methods. Together, these advances allow for a greater probability of successful recovery and analysis of evidence than was previously possible. There is also growing recognition by criminal justice professionals of the wider scope of forensic techniques and available tests.

The field of forensic deoxyribonucleic acid (DNA) analysis and the legislation that allows DNA testing on a broader number of offenders has made some of the more remarkable advances. DNA testing now allows much smaller samples of biological material to be analyzed and the results to be more discriminating. DNA testing of forensic crime scene samples can now be compared against a database of known offenders and other unsolved crimes.

Forensic laboratories have developed advanced analytical techniques through the use of computer technology. Systems such as the Combined DNA Index System (CODIS), various Automated Fingerprint Identification Systems (AFIS), and the National Integrated Ballistics Identification Network (NIBIN), were identified by the symposium as beneficial to serial murder investigations, by providing links between previously unrelated cases.

CODIS is a national automated DNA information processing and telecommunications system that was developed to link biological evidence (DNA) in criminal cases, between various jurisdictions around the United States. Samples in CODIS include DNA profiles obtained from persons convicted of designated crimes, DNA profiles obtained from crime scenes, DNA profiles from unidentified human remains, and DNA from voluntary samples taken from families of missing persons.

The CODIS data bank of these samples is comprised of three different indices or levels: the National DNA Index System (NDIS), the State DNA Index System (SDIS), and the Local DNA Index System (LDIS).

What is important for law enforcement to understand is that the information contained at the LDIS and SDIS levels may not automatically be sent to, or searched against, the NDIS level. There are different legislation requirements for inclusion into NDIS, than to LDIS or SDIS, and not all LDIS and SDIS profiles are sent to NDIS. Even when NDIS is queried, individual SDIS data banks may not be queried. Therefore, when dealing with a serial murder case, investigators need to contact their LDIS or SDIS level representatives to ensure that in addition to the NDIS databank, samples are compared in the individual SDIS data banks of each state that is of investigative interest. In cases where there is only a partial DNA profile, a national “keyboard” search can be requested through the NDIS custodian, CODIS Unit, FBI Laboratory.

AFIS is an electronic databank that compares unidentified latent and patent fingerprints to the known fingerprint file. There have been a variety of local AFIS systems in use since the 1980s. In 1999, the FBI’s Integrated Automated Fingerprint Identification System, or IAFIS, became operational. IAFIS is designated as the national repository of criminal histories, fingerprints, and photographs of criminal subjects in the United States. It also contains fingerprints and information on military and civilian federal employees. IAFIS provides positive identification through comparisons of individuals based on the submission of fingerprint data, through both ten-print fingerprint cards and latent fingerprints.

Some of the earlier AFIS systems were not compatible with the IAFIS system, and as a result, those earlier latent fingerprints may not be included in IAFIS. This becomes an issue in serial murder cases, when the offender committed offenses prior to the inception of IAFIS, as latent fingerprints from those earlier crimes will not be searchable. If there is a possibility the offender committed early crimes, the early AFIS systems need to be queried independently. Consultation with laboratory fingerprint experts may be necessary in order to establish what AFIS systems exist, which are interoperable, and the protocols required to query each system.

NIBIN is a national databank of both projectile and cartridge information. NIBIN is the integration of two previous systems: the FBI’s Drugfire cartridge case imaging system and the Bureau of Alcohol, Tobacco, Firearms and Explosives’ (ATF) Integrated Ballistic Identification System (IBIS). NIBIN is an imaging system that allows both bullets and cartridges recovered from a crime scene to be compared electronically against other bullets and cartridges recovered from previous crime scenes, in an effort to link previously unrelated cases. The system can search by geographic area or nationwide, depending upon the course of the investigation. ATF is maintaining the new system in over 75 locations, across the United States.

When conducting serial murder investigations, it is important for investigators to promptly seek guidance from appropriate forensic database experts. Such experts can provide information regarding what limitations exist and what additional queries can be made of the systems, to obtain additional investigative information.

Another area in which forensic science can play an important role is in the recovery and examination of trace evidence. Trace evidence is described as small, often microscopic material. It commonly includes hair and fiber evidence but may encompass almost any substance or material. Trace evidence may provide important lead information pertaining to offender characteristics, vehicle and tire descriptors, and environmental clues that relate to killing scenes and modes of transportation used to move bodies.

A skilled trace evidence examiner can compare the trace evidence from all of the victims in a serial murder case, in an effort to identify evidence common to all of the victims. This trace evidence will reflect a “common environment” with which all of the victims were in contact. This common environment will repeat in objects in the serial offender’s world, such as his vehicles and/or residence. This can demonstrate that all of the victims had contact with the offender at the same location(s).

Attendees at the Serial Murder Symposium universally acknowledged that serial murder cases present unique circumstances and concerns, particularly when multiple investigative jurisdictions are involved. In serial murder cases, crime scenes may occur in different law enforcement jurisdictions, each of whom may possess varying resources and abilities to process crime scenes. In some cases, agencies submit evidence to different laboratories, even though those agencies are located adjacent to one another. These issues degrade the ability of law enforcement to consistently collect evidence from a murder series. This may prevent identifying a serial killer or forensically linking previously unrelated cases to a common offender.

Attendees identified a number of forensic issues facing the law enforcement community in serial murder investigations and made the following suggestions:

• Once a series is identified, the same crime scene personnel should be utilized at related scenes to promote consistency in evidence identification and collection. Search personnel should follow established sterilization procedures to ensure there is no cross-contamination between the various crime scenes.

• Cross-contamination should be proactively prevented by using different personnel to process crime scenes than those used to collect known sample evidence from potential suspects.

• Documentation among the law enforcement agencies should be standardized to ensure continuity between separate cases.

• Aerial photographs of every murder crime scene, as well as the accompanying ancillary scenes, should be taken. Aerial photographs clearly depict the geography of the area and demonstrate the physical relationships and the distances between the crime scenes. They also identify potential routes of ingress and egress to the area.

• The number of laboratories and experts involved in serial murder investigations should be limited to properly certified facilities and personnel. Ideally, all evidence should be examined by a single crime laboratory, and that lab should utilize only one expert per discipline. If this is not possible, establish lines of communication between laboratories to ensure the sharing of pertinent information related to the investigation.

• Priority status for laboratory examinations should be obtained to ensure a quick turn around on test results.

• When consulting with forensic scientists, investigators should prioritize forensic examinations based upon their potential investigative value. In addition, forensic scientists should be consulted frequently to identify alternative sampling and/or testing that may lead to successful case resolution.

• Forensic testimony should be limited to what is needed for successful prosecution. Utilization of charts, graphs, or other appropriate audiovisual aides showing forensic linkages will clearly and succinctly convey the facts of the cases.

• When necessary, investigators should seek independent, secondary reviews of laboratory results. This may be somewhat problematic, since there are crime laboratories that will not duplicate forensic examinations. However, exceptions are sometimes made to this policy on a case-by-case basis.

Forensic evidence case vignette:

The case of serial child murderer Richard Mark Evonitz highlights the variety of forensic testing that may be utilized to solve difficult cases. In 1996 and 1997, in Spotsylvania County, Virginia, three young girls were abducted from their residences, sexually assaulted, and killed. The first case occurred on September 9, 1996, when Sophia Silva disappeared from the front porch of her house. She was found in October of 1996, in a swamp, 16 miles from her residence. A suspect was arrested and charged for her murder, based on a faulty trace evidence examination conducted by a state laboratory.

On May 1, 1997, two sisters, Kristin and Kati Lisk, disappeared from their residence after returning home from school. Their bodies were discovered five days later in a river, 40 miles from their residence. After an examination by an FBI Laboratory Examiner yielded trace evidence that positively linked the Silva and Lisk homicides to a common environment, the suspect arrested in the Silva case was subsequently released.

The investigation continued for an additional five years, until a girl was abducted in South Carolina. The victim was able to escape, and she identified Richard Mark Evonitz as her attacker. Evonitz fled South Carolina and was sighted in Florida. After a high-speed chase with police, Evonitz committed suicide. The investigation revealed that Evonitz had lived in Spotsylvania, in 1996 and 1997.

Forensic searches were conducted on Evonitz’s residence in South Carolina, his former residence in Spotsylvania, Virginia, and his car. A detailed trace examination of the evidence from these searches and the evidence obtained from the three victims revealed a number of hair and fiber matches, providing sufficient evidence to tie Evonitz to the three murders.

The following trace examinations linked Evonitz to all three homicide victims:
• Fibers from a bath mat.
• Fibers from an afghan.
• Fibers from two separate carpets in Evonitz’s former home in Virginia.
• Carpet fibers from the trunk of Evonitz’s car.
• Head hair consistent with Evonitz.

A trace examination also linked fibers from a pair of fur-lined handcuffs to the three homicide victims and the surviving victim.

The unique combination of different hair and fiber evidence yielded the “common environment” to which all of the victims and the offender were exposed.

Latent fingerprints belonging to Kristin Lisk were located on the inside of the trunk lid of Evonitz’s car, five years after the fact.