Deliberations in the murder trial of Jeffery Trevino, accused of killing his wife, Kira Steger, are scheduled to begin Tuesday after jurors hear attorneys argue their case for the last time.

On the eighth and final day of testimony Monday, prosecutors tried to dismantle defense attorney John Conard's theory that Steger's marijuana use could have contributed to her death. Conard argued unsuccessfully to dismiss the charges against Trevino, saying that prosecutors didn't prove their case and instead relied on the "urban legend that the husband always does it."

Trevino decided not to testify on his own behalf.

Trevino, 39, is on trial in Ramsey County District Court on two counts of second-degree murder. Steger was last seen alive on Feb. 21. Her body was recovered from the Mississippi River on May 8.

Over the weekend, Assistant Ramsey County Attorneys Richard Dusterhoft and Andrew Johnson investigated where Steger received her marijuana in response to a theory Conard raised on Friday.

Dusterhoft sought to admit evidence Monday that Steger's friend supplied the drug, but District Judge Leonardo Castro denied the request, noting that prosecutors could have discovered the information before trial and that the move would require the friend to incriminate herself.

Dusterhoft tried to deflate Conard's theory as he questioned retired St. Paul police Sgt. John Wright Monday. A baggie of marijuana was found in Steger's purse in her car abandoned at a Mall of America ramp.

"Does it have value?" Dusterhoft asked.

"Minimal," Wright said.

"How much?" Dusterhoft asked.

About $20, Wright said.

Dusterhoft asked the sergeant if in his 30 years as an officer, he has seen a robbery victim disposed of in a river. He said he had not.

Prosecutors believe Trevino killed Steger because she was having an affair with a co-worker and wanted a divorce. Conard doesn't think the prosecution's forensic evidence adds up, and asserts that Steger was living a secret life with an affair she kept hidden from her husband and trusted girlfriends, who testified earlier that they confronted Steger about her drinking and staying out.

After Wright's testimony, Conard motioned to dismiss the case against Trevino, which is not unusual.

Conard said the prosecution's case was "legally insufficient," and based on circumstantial evidence and "innuendo." He said the forensics weren't strong enough, and that prosecutors didn't prove that the murder occurred in the couple's bedroom.

Scientists at the Minnesota Bureau of Criminal Apprehension testified that they found several spots in the bedroom and home that tested positive for presumptive blood, and that Steger's DNA was found on several pieces of evidence, including a pillow case covered in a large red stain. Under cross-examination by Conard, they also testified that the presumptive tests they use to identify blood will show positive results when in contact with other substances.

Ramsey County Medical Examiner Dr. Michael McGee testified that Steger was cut above the left eyebrow, which would have bled "profusely."

Steger's injuries indicate that her death would have been a "screaming affair," Conard said, yet roommate Matthew Roff, who lived in the basement, didn't hear anything.

Conard dismissed prosecutors' "superhuman sleeper theory of Matt Roff."

Castro denied Conard's motion to dismiss charges. Conard rested his case without calling any witnesses.

The jury of six women and eight men, two of whom are alternates, will be sequestered for deliberations.

Twitter: @ChaoStrib