A smudge of blood on a broken window. A discarded cigarette butt. Even a used piece of toilet paper.
These are all items from which Oklahoma City police have recovered DNA evidence from burglars. Even when the criminals have not been identified and charged, their DNA profiles often are.
The department started aggressively pursuing property crime cases through DNA evidence in 2009, said Campbell Ruddock, police DNA lab manager.
Police now routinely are handling over 500 DNA cases a year, with about a 20 percent increase each year, Ruddock said.
And upward of 360 of those DNA profiles have been charged by the Oklahoma County district attorney's office in the last five years.
Finding a match
With a good, clean sample, scientists can pin a genetic match.
“A DNA profile is kind of like a combination lock. It's that specific order and combination we look for,” Ruddock said.
“We look at 16 points on the DNA. Anything beyond that is statistically irrelevant,” he said.
A solid match will put a DNA profile as being one in about 15 billion.
“To find somebody else with that DNA, you'd have to go to another planet. There aren't enough people on the Earth,” Oklahoma County First Assistant District Attorney Scott Rowland said.
Once the sample is acquired, it can be uploaded to CODIS, the FBI's DNA database.
The state then does a search for a hit, and if one is found, the sample is run again for confirmation. After another check with a second agency, the name attached to the DNA sample is released, which officers can use to file a probable cause affidavit showing enough evidence to seek prosecution from the district attorney's office.
“The DNA profile identifies a particular person. We don't know his name. We don't know what his face looks like, but we know who that person is to the exclusion of all others,” Rowland said.
“There's a lot of checks and balances going into that system to positively identify who that person is,” Ruddock said.
Stopping the clock
The statute of limitations for burglary is three years, but filing a charge against a DNA profile stops the clock, allowing the crimes to be prosecuted far into the future.
“This puts a stop to them getting a free pass just because we didn't happen to catch them within three years of the time they did it,” Rowland said.
“Instead of a warrant being issued for the arrest of ‘John Jones,' a warrant is issued for ‘DNA profile' and then a series of letters and numbers. That is ‘John Jones'. We just don't know it at the time. And whenever more evidence comes, we just amend the charge just like an alias,” he said.
“The way DNA works, it's only as good as the database you can look into. The more profiles in the database, the better chance of a hit we can get,” Ruddock said.
Sometimes burglars won't leave traces behind intentionally, but others will open a can of beer and take a swig or chomp a few bites from an apple, Ruddock said.
And about half a dozen cases each year are gleaned from fecal samples left at the burglarized home, he said.
Grease smudges from skin contact with surfaces also are becoming a more common method to trace burglars, Ruddock said.
“DNA is not magic. It will not solve crimes by itself, but it will place a person at a particular location or in possession of a particular item, and many times that's all you need,” Rowland said.
But it takes good, old-fashioned police work to get the necessary sample to prosecute criminals.
“The lab is only as good as the guys on patrol and what they collect,” Ruddock said.
The results speak for themselves. In 2012, of the 294 total DNA hits received from samples, 233 of those were property crime cases, Ruddock said.
Aside from samples given consensually, the DNA hits result from samples required of convicted felons.
“A lot of these guys tend to be repeat offenders. A lot of these guys migrate from burglars to rapists and murderers,” Ruddock said.
“The ability to prevent crime is surely better than cleaning up violent crime at the end of the day,” he said.
“There's no way to quantify how many of those we might have intervened on,” he said.
Rowland doesn't know that he has ever seen somebody who's just committed one residential burglary.
“These criminals do strings of them, and so even if they just leave DNA at one location, many times you'll wind up solving a handful of others and preventing numerous other ones in the future by taking them off the street,” Rowland said.
“As far as generating hits and closing out cases, it's been very successful,” Ruddock said.
“We're just sick and tired of burglars and thieves. I know people are sick of burglars and thieves,” Rowland said.
“I've been the victim of a burglary. We've just had it, and I know the public has had it. This is allowing us to at least fight back against a crime that is so numerous and heretofore has sometimes gone unsolved.”