Photo courtesy of Connecticut State Police

Three years of the most serious criminal investigations in Connecticut show that forensic analysis of biological evidence, including DNA, has skyrocketed.

However, the audit of homicide, rape, robbery, burglary and assault cases showed physical evidence did not impact conviction rates, while it still may assist with making homicide arrests, concludes the U.S. Department of Justice report written by a University of New Haven criminal justice scholar.

“This study tracked the submission, analysis and dissemination of forensic evidence of a significant number of cases in the State of Connecticut,” they write. “This study shows homicide is the only crime in which evidence has a significant relationship with arrest… Physical evidence does not impact conviction outcomes. The only exception is assault, which this study found to be positively influenced by forensic evidence.”

The paper assessed crimes in Connecticut from 2006 to 2009.

That included cases submitted to the state crime lab for assault (1,201), burglary (3,442), robbery (1,075), rape (1,829), and homicides (438).

The path the evidence took, from collection to submission to analysis to presentation in court, was compared to a similar 2010 study of national forensic evidence handling for the year 2003.

The biological submissions dramatically increased from the previously studied 2003 rates to the three-period in Connecticut just a few years later. That spike was shown across the board, for homicide (from 38.3 percent to 89.7 percent of cases), assault (from 4 to 30.8 percent), rape (53.5 percent to 94.2 percent), robbery (1 to 47.3 percent), and burglary (1 percent to 32.3 percent).

Collection of other kinds of evidence generally increased, as well – but with a notable exception of firearms and weapons in homicides.

The forensic evidence that was collected had a much higher submission and examination rate than in the 2010 study, as well. The examination rates for assault, robbery, rape and burglary all increased to well over 80 percent, where they had previously mostly been in the single-digit percentages.

But the outcomes were mostly dependent on the circumstances of detection. The physical evidence was important, but did not seem to influence crime solving as much as identifications, interrogations, confessions, and witnesses did among the thousands of cases.

“It seems investigative factors and victim/offender relationships tend to influence case outcomes more than physical evidence,” the authors add.

Other takeaways include:

  • Assaults – weapons and firearms evidence were submitted in 70 percent of cases, while 30 percent of cases included biological evidence.
  • Burglaries – nearly 70 percent of cases included fingerprint submissions, and 32 percent included biological submissions. These cases had the lowest conviction rate, at 11.9 percent.
  • Robberies – cases incorporated a mix of biological (47 percent), fingerprint (44 percent), and weapons (23 percent). Approximately 32 percent of these cases ended in a conviction.
  • Rapes – almost all the cases included biological submissions, with another 5 percent including trace evidence from the scene. These cases produced a 17 percent conviction rate.
  • Homicides – almost all cases had evidence submitted for examination, and examination took place in 85 percent of them. Almost all the evidence submissions included biological, but there were also weapons evidence and fingerprints. About 35 percent of the homicides had evidence that directly linked the suspect to the crime. Off the cases with information available, some 44.5 percent ended in a conviction – and that is where the forensic evidence made the biggest impact, according to the report.

Shortly after the period of the study, Connecticut was declared the biggest DNA-sample backlog in the nation. The load became so great that in 2012, state officials asked law enforcement to limit the number of submissions to the crime lab, according to the report. That backlog was apparently mostly cleared by the end of 2015, according to local media.

Surveys were also taken of the state’s detectives. Those investigators rated DNA the most important in virtually every kind of crime investigation, which did not match the data collected.

“Investigators do not have accurate view on what evidence helps the most for different crime types,” the authors conclude.