FARGO, N.D. – A judge in North Dakota's first federal death penalty case asked attorneys Thursday to narrow their arguments before he decides whether to dismiss the appeal filed by the man convicted of killing a college student 10 years ago.

U.S. District Judge Ralph Erickson told lawyers there appears to be "insufficient factual evidence" for Alfonso Rodriguez Jr.'s appeal to continue. However, he declined to make a final ruling and said it was too early to determine if the appeal could be dismissed without a hearing. He instructed attorneys to revise their arguments.

"If we can narrow those issues, I would appreciate it," Erickson said.

A jury in 2006 convicted Rodriguez of kidnapping and killing University of North Dakota student Dru Sjodin, of Pequot Lakes, Minn.

Lawyers for Rodriguez Jr., of Crookston, Minn., appeared in Fargo to update on the habeas motion, generally considered the last step in the appeal process. Rodriguez's attorneys filed the appeal in October 2011, claiming among other things that Rodriguez is mentally disabled and his trial lawyers did a poor job of defending him. Prosecutors said the appeal has no basis and asked Erickson to dismiss the motion.

Sjodin was abducted from the parking lot of a Grand Forks shopping mall in November 2003. Her body was found five months later near Crookston, where Rodriguez lived with his mother. He had been released from prison earlier in 2003 for other crimes that included rape and attempted kidnapping.

The appeal describes Rodriguez's troubled childhood and claims he was sexually abused when he was 6 years old. Rodriguez allegedly told a psychiatrist that Sjodin resembled the woman who abused him, triggering post-traumatic stress disorder symptoms, according to the psychiatrist.

Prosecutors scoffed at the notion that Rodriguez's trial lawyers should have sought an insanity defense. The government said two medical experts concluded he is not mentally disabled and didn't kill Sjodin by accident, as the appeal claims.