ONLY ON ABC7NEWS.COM: Defense in Hillsborough murder case reveals theory

HILLSBOROUGH, Calif. (KGO) -- Last Thursday, ABC7 News learned exclusively that a suspect in a high profile murder case on the Peninsula cut a deal with prosecutors, pointing the finger for the killing at the other two suspects.

Olivier Adella is expected to testify that Tiffany Li and her boyfriend Kaveh Bayat were responsible for the murder of Keith Green, the father of Li's two children.

TIMELINE: EXCLUSIVE: Suspect in Millbrae man's murder cuts deal with prosecutors

After his testimony at trial slated for September, Adella will be freed on parole.

Prosecutors believe Bayat fatally shot Green in April 2016 and that Li orchestrated the murder.

They also believe Adella is only guilty of disposing of the body.

"He wanted a deal. it's something he's been asking for, almost begging for," said Li's attorney May Mar.

TIMELINE: Peninsula murder mystery: Death of Millbrae resident Keith Green

Tiffany Li's attorneys Geoffrey Carr and Mar tell ABC7 News they believe Adella is trying to save his own skin and that he's the one who murdered Green.

Carr read a polygraph test which an expert said Adella flunked.

"Did you shoot Keith Green?" Carr quoted the test. "He answered 'no'."

"His reaction was consistent with someone being deceptive regarding that issue," Carr added.

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Li's attorneys would not respond to questions about Bayat's possible involvement, but they did pose a theory on what happened the day Green was killed.

"Mr. Adella and potentially confederates were seeking a gun, and they may have ultimately gotten one, and they were involved in a kidnap attempt of Mr. Green."

District Attorney Steve Wagstaffe says polygraph tests are not reliable in court.

"Every court in the land including every court in California has held that these are inadmissible," said Wagstaffe.

Adella's attorney did not return our calls.

Click here for full coverage on the investigation into the death of Millbrae father Keith Green.