April 23, 2014
Oregon State Police
Forensic Services Division
Portland Forensic Laboratory
The Oregon 5K
Using Combined DNA Index System (CODIS) to solve crimes
Athletes take heed! The Oregon 5K is not a running event. In fact, there is no finish line. The participants are not winners, only losers who were forced to register by law. And the top prize awarded is… jail time. Even so, the Oregon 5K is thrilling, as it refers to achieving 5000 hits (i.e., crimes linked or solved) using CODIS (the Combined DNA Index System). Oregon achieved this historic 5K milestone in 2013, one of only a dozen states to go so far, so fast.
How does CODIS work? CODIS blends forensic science, computer technology, and dedicated staff into an effective tool for solving crime. CODIS enables federal, state, and local crime labs to exchange and compare DNA profiles electronically, thereby linking crimes to each other and to convicted offenders. A “hit” occurs when we are able to match an unsolved case to a convicted offender, or to another unsolved case.
The Oregon State Police began DNA testing in 1990. After a two-year validation period, the unit began using the (older) RFLP technique in February of 1992. In 1999, the laboratory transitioned to utilizing the newer STR DNA technique. STR testing remains the national standard today, used in crime laboratories throughout the U.S.
Oregon’s first hit occurred in 1994. Hit #1000 came after twelve years (2006). Hit #5000 arrived just seven years later (2013). Predictions for the arrival of hit #10,000 vary widely, and depend upon projections for staffing levels, technology changes, and the total number of samples in CODIS.
What samples are in CODIS? DNA profiles are generated from biological material left at a crime scene by a perpetrator, and are entered into the CODIS database. Also in the database are DNA profiles acquired from known individuals convicted of past crimes. On September 29, 1991, the Oregon Legislature passed a law requiring sex offenders and murderers to submit blood samples to the Oregon State Police DNA unit for databasing purposes. In 1999, the law was expanded to include first-degree burglary and assault convictions, and the collection process was simplified to using oral swabs instead of blood. In 2002, the law was again expanded, this time to include all felony convictions. This significantly boosted the number of submissions and, consequently, the number of CODIS hits (Figure 1.)
Figure 1. Oregon State Police CODIS hits, by year. A decline during 2003 reflects the temporary lay-off of 75% of laboratory staff.
Oregon State Police have over 160,000 convicted offender samples and over 8000 forensic samples in the Oregon DNA database. These are compared weekly to over 12 million samples in the National DNA database. The majority of offender DNA collections arrive from the state prison intake center. A significant number are also collected by parole or probation officers. Approximately one hit is made for every 36 offender DNA samples received.
Is CODIS effective? CODIS hits are the combined result of effective offender collections and casework evidence submissions. While person crimes are usually highlighted by the media, approximately 75% of cases solved by CODIS hits involve property crimes, for which there is a high repetition rate (Figure 2).
Fig 2. Crimes Solved by Oregon CODIS hits. Blood and oral evidence is commonly left behind at burglary scenes, yet some states do not routinely investigate burglary cases.
You’re likely familiar with the term “gateway drug”, but have you heard about “gateway crime”? Oregon offender DNA samples can be submitted for any felony conviction, and often solve crimes which are dissimilar to the original conviction/DNA submission. For example, a convicted rapist might subsequently commit a homicide crime, and drug offenders needing funds for their addiction often commit burglary crimes (Figure 3).
Fig. 3. Offender's Collection Crime prior to CODIS Hit. Almost half of submissions are from Burglary and Drug offenders, yet these gateway crimes can link to any type of investigation.
The Oregon 5K includes hits to cases in 35 of Oregon’s 36 counties (Figure 4). Not unexpectedly, these are mainly in counties with higher populations, and along the I-5 corridor.
Fig 4. Number of hits in each Oregon county. Over 60% of hits come from just three counties in the Portland Metro area.
CODIS also allows the DNA database to assist in solving crimes in other states. The Oregon 5K includes over 700 interstate hits. Most commonly, hits are made to the states immediately North and South (Washington and California), but Oregon DNA matches have been made to 40 states across the country (Figure 5). A recent international hit also solved a 1970s homicide in Canada, thus emphasizing that crime knows no boundaries.
Fig 5. Number of Oregon hits with other states. Proximity and database size are major factors affecting the number of hits with other states.
Are there any CODIS limitations? Two primary limitations are funding and the law. Available resources have limited the program in years past. Oregon relied upon grant funding to outsource the processing of offender DNA samples, and some staff continue to be grant-funded. However, since 2012, the processing has been done in-house, with a turnaround time of approximately 43 days from sample intake to database entry.
The law limits CODIS in two ways. First, Oregon has a statute of limitations (SOL) which limits convictions for most crimes to only three years after the date of commission. Because of the timing of offender DNA collections, older cases are being matched to offender DNA profiles after four or five years. Consequently, these “SOL”-cases can’t be pursued by the agency. It can be disheartening to know that the victims and perpetrator will not receive justice. In 2013, over 5% of DNA matches were past the statute of limitations.
Second, Oregon’s law does not allow DNA collection from arrestees. Over half the states in the US have implemented DNA collection from arrestees, and some states have seen a 50% increase in hits as a result. In addition, having the DNA sample earlier could reduce the number of “SOL”-cases by making a DNA match sooner.
What’s next for CODIS? A high-throughput project was begun in 2013, allowing a streamlined approach to sample collection and processing of property-crime samples, which are a significant component of the Oregon 5K (Figure 6). Several law enforcement agencies have been trained to collect the DNA evidence onto specialized swabs, and can submit up to three swabs to the lab. With minimal handling and processing, DNA on the swabs is extracted and the DNA profiles generated much more quickly than through the normal submission chain. This can clear a case in 30 days instead of 120 days! In 2014, the Oregon State Police hope to expand this program throughout the state.
Fig 6. Annual Hits by Category of Crime Solved. Steep drops in property-crime hits were caused by loss of grant funds to process these cases.
Also on the horizon is the adoption of a “mega-plex” kit. The FBI is increasing the minimum core CODIS loci required for database entry. Currently, 13 chromosomal locations are required, but this will expand to 22 different chromosomal locations. The Oregon State Police will therefore transition to using a different DNA profiling kit with enhanced information. After that, we’re on our way to achieving 10K.