A supermarket tabloid has offered actor Robert Blake $100,000 to take a polygraph test to clear himself of suspicion in the mysterious murder of his wife.

While so-called lie-detector tests are generally not allowed as evidence in court, Star editor-in-chief Tony Frost said yesterday Blake has nothing to lose. 

"If Mr. Blake has nothing to hide, what better way is there of removing the umbrella of suspicion?" Frost told The Post

"The results of a polygraphs are not admissible in a court of law, but they do go a long way to convincing the court of public opinion." 

An unidentified gunman killed Blake's wife, Bonny Lee Bakley, shortly after she and the former Baretta TV star had dinner at a Los Angeles restaurant May 4. 

Blake claims he walked Bakley back to their car, but had to leave her alone briefly to retrieve a licensed gun he had left at the restaurant. That's when Bakley was shot to death, he has said. 

Bakley's relatives have said they don't believe Blake's story. 

Blake's lawyers could not be reached for comment. 

Frost said his magazine has never asked a celebrity to take a polygraph, but the public interest in Bakley's murder prompted the test-for-cash challenge. 

The Star has retained Los Angeles-based polygraph expert Joseph Paolella, formerly of the Secret Service, to administer the test if Blake takes the bait. 

Paolella said he'd ask Blake just four questions: Did he kill Bakley, know who killed her, arrange the killing, or have access to a Walther handgun? 

ABC news has reported that a German-made Walther was the murder weapon.