Aggregated News

HARTFORD, Conn.—

When police in southern Louisiana were investigating the deaths of eight women in 2009, the sophistication of the crimes set off rumors that the serial killer was a police officer -- speculation that became so pervasive that officials ordered DNA testing of law enforcement personnel to rule it out.

All local officers agreed to the testing and were eliminated as suspects, but the killer remains at large, said Jefferson Davis Parish Sheriff Ricky Edwards.

Having officers' DNA samples on file is important for saving time in investigations and fending off doubt about evidence at trials because it allows authorities to identify unknown genetic material found at crime scenes, Edwards and other police and crime lab officials say.

Police in other parts of the country, however, are not as willing to hand over their DNA. Rank-and-file police from Connecticut to Chicago to Los Angeles have opposed what some experts say is a slowly emerging trend in the U.S. to collect officers' DNA.

"From a civil liberties standpoint, there are a lot of red flags," said Connecticut Trooper Steven Rief...