Attorneys for the man accused of abducting college student Dru Sjodin from a shopping mall parking lot and killing her rested their case Tuesday after calling just one witness.

Closing arguments in the trial of Alfonso Rodriguez Jr. were expected Tuesday afternoon, and U.S. District Judge Ralph Erickson told jurors to expect to begin deliberations later in the day.

The only defense witness was George Sensabaugh Jr., a forensic science professor from California who testified Tuesday that tests for sexual assault were not reliable.

Rodriguez, 53, a convicted sex offender from Crookston, Minn., has pleaded not guilty to a charge of kidnapping resulting in death. Prosecutors have said they will seek the death penalty if he is convicted.

Sjodin, 22, a University of North Dakota student from Pequot Lakes, Minn., was abducted at the Grand Forks shopping mall on Nov. 22, 2003. Her partially decomposed body was found the following April in a ravine near Crookston.

Under questioning by Assistant U.S. Attorney Keith Reisenauer, Sensabaugh testified that he knew few details about the Sjodin case and based his testimony on information from the autopsy and lab work.

Defense attorney Robert Hoy argued that prosecutors didn't prove Sjodin was alive when she was abducted.

He asked the judge to acquit Rodriguez, but Erickson denied the motion.

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Prosecutors, who called 52 witnesses, had opened the third week of testimony by interviewing a medical examiner who said he believes Sjodin's neck was slashed at the site where her body was found.

McGee, the medical examiner in Ramsey County, Minn., said he found evidence Sjodin was sexually assaulted. The assault could have happened up to 36 hours before her death or after her death, he told jury Monday.

Prosecutors said Sjodin's hands had been bound behind her back and she was nude from the waist down, with a rope and remnants of a plastic bag around her neck.

McGee said that while the neck wound was the most likely cause of death, Sjodin could have suffocated from a plastic bag over her head or died of exposure. He said he could not pinpoint the exact cause of her death.