A former Honolulu police lieutenant who is scheduled to begin serving a 3-1/2-year prison sentence next month in Hawaii’s biggest ever corruption case is asking a judge to let him remain free while he appeals his conviction.

Derek Wayne Hahn’s attorney said Wednesday that the appeal could take several years.

A jury convicted Hahn, another former police officer, a former Honolulu police chief and the ex-chief’s former prosecutor wife of conspiracy in a plot to frame a man.

Hahn helped Louis and Katherine Kealoha, the former chief and the former prosecutor, with the framing of the man to preserve the couple’s lavish lifestyle, prosecutors said.

Hahn is scheduled to surrender at a federal detention center in Oregon on June 1.

The appeal to the 9th U.S. Circuit Court of Appeals will focus on instructions to jurors before they deliberated and other issues, said Hahn’s motion by Sacramento, Calif., attorney Timothy Warriner.

A U.S. judge in Honolulu will consider the request at a hearing May 25.