Kipland Kinkel continues to challenge his prison sentence of nearly 112 years for fatally shooting his parents and then killing two students at Thurston High School and wounding 24 others more than 20 years ago.

The U.S. Supreme Court last year refused to review Kinkel’s sentencing, meaning the Oregon Supreme Court’s ruling upholding his sentence stands.

This year, though, Kinkel, now 37, filed a new motion in federal court, seeking to certify two questions before the state’s high court . Both stem from his age — 15 — at the time of the mass shooting.

First, does the Oregon Board of Parole and Post-Prison Supervision have authority to release him — a juvenile offender — to post-prison supervision?

Second, does state law allow the parole board to consider whether he’s capable of rehabilitation after serving 25 years in custody, which would be May 2023? Kinkel’s sentence now doesn’t allow for his release until Jan. 21, 2110.

Kinkel’s lawyers argue that the lengthy sentence amounts to cruel and unusual punishment because it affords a juvenile offender no possibility of release “where no finding was made by the sentencing court that Mr. Kinkel’s crimes reflected irreparable corruption.”

Oregon Assistant Attorney General Samuel A. Kubernick counters that Kinkel’s request should be denied because he’s not entitled to a parole or murder review hearing until after he has served 25 years.