BISMARCK, N.D. (AP) - The defense rested its case Friday in the murder trial of Moe Gibbs after calling a DNA analysis expert.

Both sides now may call witnesses to rebut earlier testimony. Prosecutors immediately called Bureau of Criminal Investigation agent Tim Erickson, to discuss the use of Gibbs' computer.

Gibbs, 35, a former Barnes County jailer, is charged with murder in the September 2006 death of Mindy Morgenstern, 22, a Valley City State University student from New Salem. The trial is wrapping up its second week of testimony.

Authorities say Gibbs' DNA was found on the fingernails of Morgenstern's left hand.

A DNA analysis expert called by Gibbs' attorneys Friday said there may be an innocent explanation for that.

"I still believe Mr. Gibbs' DNA could have been transferred through non-criminal activity, because there was contact between these individuals," Marc Taylor said.

Prosecutors questioned the qualifications of Taylor, who owns a genetic testing lab in Ventura, Calif.

Gibbs' attorney, Jeff Bredahl, has said the DNA on Morgenstern's fingernails could have been from an object that both Gibbs and Morgenstern touched. The two lived in the same apartment building.

Bredahl said DNA could have been transferred when Gibbs picked up Morgenstern's laundry basket to help her carry laundry to her apartment, and Taylor agreed that such a transfer was possible.

Jonathan Byers, an assistant attorney general, challenged Taylor's qualifications as an expert. Taylor has a bachelor's degree in zoology.

Byers presented Taylor with two examples of publications that listed Taylor as having a master's degree. Taylor said he did not.

Earlier, Taylor said someone who wipes a runny nose could transfer genetic material. Gibbs' lawyers have hinted Gibbs was having problems with a runny nose at the time of Morgenstern's death.

The audio files below are from the Gibbs trial and are provided by the Associated Press.

Description of the audio files:

Taylor DNA Transfer is Marc Taylor, a DNA expert speaking as a Gibbs defense witness, saying Gibbs' DNA could have gotten onto Mindy Morgenstern's fingernails innocently. Bredahl Taylor DNA Transfer is Taylor speculating about whether the DNA transfer may have come from Gibbs and Morgenstern handling the same laundry basket. The first speaker is Jeff Bredahl, a Gibbs defense attorney, followed by Taylor. Byers Taylor DNA Transfer 2 is Taylor saying that he doesn't know of a published article describing a "touch DNA transfer" in which the recipient got 30.8 nanograms of DNA. According to earlier testimony, 30.8 nanograms of Gibbs' DNA was found on Morgenstern's fingernails. Taylor says that is a larger amount of DNA that is usually found in a "touch DNA" situation.