INDIANAPOLIS - Forensics, a constantly evolving science, is increasingly critical in leading to arrests and convictions in high-profile cases, including the explosion on Indianapolis' south side.
Six months after the Richmond Hill explosion, sources told RTV6 that they have a "good idea" of who the fourth suspect is, that there is no pending arrest and that are "building a case" that will stick in court.
Indianapolis Director of Homeland Security Gary Coons told Call 6 Investigator Rafael Sanchez that the case remains active and that he can't comment on the ongoing investigation.
Coons added that evidence is still being processed and that the public can still call Crime Stoppers to provide tips regarding the explosion.
The search for a fourth suspect has been a top priority for law enforcement since arresting Ray Leonard, his girlfriend, Monserrate Shirley, and his brother, Robert Leonard, in December on arson and murder charges.
The night of the Nov. 10 blast, witnesses told police they saw two men in a white van hours before the explosion that killed Dion and Jennifer Longworth and destroyed and damaged several homes.
One of the men believed to be in the van was Robert Leonard, who remains in custody. The passenger has yet to be officially identified.
Unsealed search warrants show police had further evidence of a fourth suspect less than a month after the incident.
Court documents indicate that investigators recovered the front door of the home at 8349 Fieldfare Way, where the explosion originated.
Forensic scientists found DNA samples on the front door belonging to an unidentified adult male.
Scientists at the Marion County Forensic Services Agency declined to talk about the ongoing investigation.
"DNA is the 'aha' moment in forensic science," said Mike Melder, director of the Marion County Forensic Services Agency. "If we can identify a person in a crime or can exonerate an individual, that's good, too."
Items from the south side explosion were among 51, 511 total the agency processed last year, involving more than 12,425 cases.
"There is some times that I will start with a sample and I think there is no way to develop a profile from this and I give it a shot and then I develop a profile and I actually link that profile to an individual," said Tonya Fishburn, a forensic scientist.
The efforts of Fishburn and her colleagues since 2008 have cracked cases based on DNA found on hoodies, lip balm and a telephone cord.
"Currently, the procedure we use to conduct DNA analysis all we need is a billionth of a gram," said Dr. Muhammad Amajed, the lab's DNA technical leader.
Advances in the science allowed the lab to crack a cold case last year.
DNA led to the conviction of Paul Reese nearly three decades after he killed a teenage girl in Marion County.
Last month, an Indianapolis school administrator went to jail after having sex with a student. A key piece of evidence was an item he used to clean himself with that had his DNA.
In Boston, DNA is playing a major role in the marathon bombing.
Technicians found DNA belonging to a female on one of the devices, expanding the investigation beyond the two men initially considered responsible for the act of terror.
The Indianapolis lab's budget is tight, but to keep up with the demand, new technology will go into operation in a couple of days.
Currently, analysts can manually process 30 samples at a time, but a new machine will run 80 at a time in search of DNA.
"Some of these cases are so complicated, you wouldn't think you be able to find anything, but we have," said Medler.
Currently, the lab is turning around samples within nine weeks. The goal is to get that down to six weeks.
DNA is commonly referenced in a number of television shows, such as ABC's "Castle" and "Body of Proof," which has affected the opinion of the general public, specifically potential jurors who expect to see scientific evidence during trials.
A 2008 study found that 73 percent of jurors want to see scientific evidence in murder cases, 71 percent in rape cases and about 50 percent in breaking and entering cases.