When Tammy Klein began investigating crime scenes eight years ago, it was virtually unheard of for a killer to use bleach to clean up a bloody mess.

Today, the use of bleach, which destroys DNA, is not unusual in a planned homicide, said the senior criminalist from the Los Angeles County Sheriff’s Department.

Klein and other experts attribute such sophistication to television crime dramas like “CSI: Crime Scene Investigation,” which give criminals helpful tips on how to cover up evidence.

Prosecutors have complained for years about “the CSI effect” on juries – an expectation in every trial for the type of high-tech forensic evidence the show’s investigators uncover. It also appears the popular show and its two spin-offs could be affecting how some crimes are committed.

“They’re actually educating these potential killers even more,” said Capt. Ray Peavy, also of the Los Angeles County Sheriff’s Department and head of the homicide division.

“Sometimes I believe it may even encourage them when they see how simple it is to get away with on television.”

A man charged in a recent double-homicide in northeast Ohio was a “CSI” fan and went to great lengths to cover his tracks, according to an affidavit filed by Trumbull County prosecutors.

Jermaine “Maniac” McKinney, 25, allegedly broke into a house, killed a mother and daughter and used bleach to remove their blood from his hands, prosecutors said. He also allegedly covered the interior of a getaway car with blankets to avoid transferring blood.

Prosecutors said McKinney burned the bodies, his clothing and removed his cigarette butts – which would contain his DNA – from the crime scene.

According to the affidavit, he also tried to throw some evidence into a lake, including a crowbar used to bludgeon one of the victims. The lake was frozen though and he shouted a profanity when the crowbar remained on the surface. Investigators later recovered the evidence. McKinney, who was indicted this month on two counts of aggravated murder, aggravated burglary and other charges, could face the death penalty if convicted.

Cases where suspects burn and tamper with evidence seem to be increasing, said Chuck Morrow, chief of the criminal division in the Trumbull County Prosecutor’s office.

“People are getting more sophisticated with making sure they’re not leaving trace evidence at crime scenes,” Morrow said.

Klein said most crimes aren’t well-planned and that detailed attention to prevent leaving trace evidence typically occurs in cases where someone has killed a family member or business partner.

“For the most part, our killings involve gangbangers who, for the most part, are pretty stupid,” she said.

Sophisticated planning and concealment of evidence are aberrations, not the norm, said Larry Pozner, former president of the National Association of Criminal Defense Lawyers.

“Most people who commit crimes are not very bright and don’t take many precautions,” Pozner said. “CSI and all the other crime shows will make no difference.”

Yet, in the six years since CBS, which did not return phone calls seeking comment, introduced “CSI,” there’s been a trend of fewer clues like hair, cigarette butts and the killer’s blood left behind at crime scenes, Peavy said.

The more sophisticated the television story lines get, the better equipped criminals will be, Peavy said, adding that he never watches “CSI” because it’s too unrealistic.