He pleaded guilty to 2nd degree murder for the killing of Jane Bashara with the condition that he must testify in any proceedings if called to do so.
Sources say he will testify against Bob Bashara.
Gentz has long claimed that Bashara was the master mind behind the killing.
Watch Uncut: Gentz pleads guilty to murder.
Judge Voland Evens told Gentz he could face life in prison with his plea.
But, she said she would likely sentence him to no less than 17 years and a maximum of 28 years in prison.
The official sentencing for Gentz will be on January 29th
Gentz was charged with murder and conspiracy in death of Jane Bashara, whose body was found in her Mercedes-Benz in January.
She was found dead in the back of the SUV in a Detroit alley.
Jane had been reported missing the night before.
Gentz did odd jobs Jane Bashara's Bob Bashara. Bashara was sentenced to 80 to 240 months in prison for trying to hire somebody to kill Gentz in jail.
During his sentencing Bashara said he is "truly and humbly sorry" for hiring a hit man to kill the man who is the suspect in his wife's slaying.
"What I did was inexcusable. I have no one to blame but myself," the Grosse Pointe Park man told the court. "But I understand fully what I did was a crime and something that I will regret for the rest of my life."
Bob Bashara is not charged in his wife's death.
Special Section: Grosse Pointe Park murder case
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