NASHVILLE, Tenn. (AP) — A Tennessee death row inmate asked the state Supreme Court on Thursday to vacate his execution date so that an appeals court could review new evidence in his case.

Oscar Smith, 71, is scheduled to receive a lethal injection April 21. He was convicted of fatally stabbing and shooting his estranged wife, Judith Smith, and her sons Jason and Chad Burnett, 13 and 16, at their Nashville home on Oct. 1, 1989. Smith has maintained that he is innocent.

Earlier this month, Smith asked the Davidson County Criminal Court to reopen his case after a new type of DNA analysis found the DNA of an unknown person on one of the murder weapons. The judge denied that request as well as a second request to reconsider, writing that the evidence of Smith’s guilt was extensive. Smith has appealed to the Criminal Court of Appeals and asked for an expedited hearing.

In a Thursday motion, Smith’s attorneys asked the Tennessee Supreme Court to halt Smith’s execution so that the Appeals Court could have time to fully consider the new evidence. They argue that the Criminal Court judge incorrectly applied the law when it denied Smith’s request to reopen his case.

Smith previously sought to prove that fingerprint evidence used against him was unreliable. In Thursday’s motion, Smith’s attorneys argued the combination of a fingerprint and DNA from an unknown person on one of the murder weapons should be considered together as strong proof of his innocence.