(CNN) -- It's a familiar scenario: When clues are scarce, witnesses won't talk and police are stymied, they turn to DNA.
The genetic building blocks can identify a victim, implicate a suspect or clear the wrongly accused. Now the science is expanding beyond human beings.
Researchers have developed a database of canine DNA, and law enforcement officials are hoping it can help prosecute people who run dogfighting rings.
Dogfighting is an underground "blood sport" that is difficult to track, and it's often impossible to prove a case against suspects accused of promoting and participating in dogfights, said Dr. Melinda Merck, senior director of veterinary forensic sciences with the American Society for the Prevention of Cruelty to Animals.
But because the dogs are highly inbred for their fighting qualities, their bloodlines may provide the evidence investigators need.
The Canine CODIS (Combined DNA Index System) is similar to the human DNA index system used by the FBI. And, it's ready to be used to investigate and prosecute dogfighting operations, Merck said.
While investigating one of the largest dogfighting rings last year in U.S. history, Merck teamed up with officials at the ASPCA, The Humane Society of Missouri and researchers at the Veterinary Lab at University of California, Davis, to create the Canine CODIS system.
The 18-month investigation involved federal, state and local law enforcement agencies and led to the arrest of at least 19 people in July 2009 in five states. Some 400 dogs were confiscated, and investigators say they were bred for dogfighting.
After the DNA samples were collected, Merck and her colleagues turned for help to the Veterinary Lab at the University of California, Davis. They asked the lab to set up an operation similar to the FBI's CODIS to analyze the data, which they hope will link dogs to those collected in other cases.
"We wanted to link different defendants together, some across state lines," Merck said, explaining that the dogs' bloodlines can now be traced across generations. "If we find one location where there was a first-generation breeding, we could connect them to different dogs from a different crime scene."
The ASPCA says the database will help investigators establish connections between dog breeders, trainers and operators by using canine blood collected during suspected dogfighting raids.
Once the program was up and running, Merck was able to link DNA from 100 dogs. Today, the lab has DNA specimens from more than 400 dogs, she said.
The 2007 dogfighting prosecution of NFL star quarterback Michael Vick focused national attention on dogfighting. Vick pleaded guilty in 2007 to a federal charge that he bankrolled a dogfighting ring from his Virginia home.
Merck, who took a lead role in the Vick investigation, says the Vick case expanded public awareness of a federal crime that generates millions of dollars, she says.
Vick, who played for the Atlanta Falcons for six seasons, pleaded guilty in the federal and state dogfighting cases and served 21 months in prison. He was suspended from football and declared bankruptcy. He returned to the field in 2009 and now plays for the Philadelphia Eagles.
Vick spoke last week to students in Snow Hill, Maryland, urging them to make the "right decision" in life. Responding to a question from a student, Vick said that while growing up, he never saw dogfighting as wrong, said the school's principal, Tom Davis, who attended Vick's talk with the students.
Although there are no official statistics, the ASPCA estimates that tens of thousands of people are involved in dogfighting, which is a felony in all states.
Merck hopes the canine DNA database will grow as law enforcement officials from the U.S. and abroad contribute samples.
"If you got the dogs, you got the DNA," Merck said. "I think it's going to be interesting to see how this database enhances criminal cases. It should make dog-fighters very nervous."