PORTLAND, Ore. (AP) — An Oregon man who questioned the integrity of the police investigation that led to his prosecution has won release from prison eight years into a 20-year sentence for hiring a hit man to kill an acquaintance.

The Oregonian/OregonLive reports the state won’t say why it agreed to slash Gary Tiffee’s sentence, but his appeal paints a cozy association between the Springfield detective who investigated the case and the informant he relied on.

Tiffee, 57, of Springfield was convicted in 2012 in a murder-for-hire plot involving an acquaintance, a scheme captured on a court-approved body wire. He pleaded guilty as part of a plea agreement.

He walked out of the Oregon State Penitentiary Nov. 1.

It’s not uncommon for a conviction or sentence to be altered during a court review process known as post-conviction relief. The process typically focuses on the quality of the defense or other legal issues.

Tiffee’s appeal, however, centered on what his lawyer characterized in court filings as police misconduct. A Springfield police lieutenant named Scott McKee alerted Tiffee to potential misconduct by the investigating officer.

This fall, the state agreed to drop Tiffee’s convictions for conspiracy to commit aggravated murder and solicitation to commit aggravated murder. His attempted murder conviction remains.

Tiffee’s sentence was reduced to seven years and six months. He got credit for time served.