The defense strategy in the murder trial of Jeffery Trevino took an unexpected turn late Friday when his attorney raised the specter that Kira Steger's marijuana use could have played a role in her death.

Trevino's attorney, John Conard, showed pictures authorities took of a baggie of marijuana found in Steger's purse. He then asked retired St. Paul police Sgt. John Wright if marijuana dealers and buyers are robbed with "surprising frequency" in St. Paul.

Wright said they are robbed, but he wasn't sure if "surprising frequency" was an accurate assessment. When Trevino reported Steger, his wife, missing on Feb. 24, he told police he was worried about her sudden increase in drinking, staying out late and her marijuana use.

Trevino, 39, faces two counts of second-degree murder in Ramsey County District Court for allegedly killing Steger, 30. The St. Paul woman was last seen alive Feb. 21. Her body was recovered May 8 from the Mississippi River.

Over the last seven days of testimony Conard has focused on casting doubt on the prosecution's forensic evidence. Friday's cross-examination could lay the foundation for the argument that someone else killed Steger.

Conard asked Wright if he knew where Steger received her marijuana or if he asked her friends about it.

No, Wright said.

The issue was explored briefly before court recessed for the weekend. Assistant Ramsey County Attorneys Richard Dusterhoft and Andrew Johnson haven't had a chance to address the subject.

Testimony will resume at 9 a.m. Monday with Conard cross-examining Wright.

One of Steger's close friends testified earlier in the trial that Steger used the drug recreationally. Ramsey County Medical Examiner Dr. Michael McGee testified that toxicology tests showed no tetrahydrocannabinol, or THC, the principal chemical substance in marijuana, in her system.

The baggie of marijuana was found in her purse, which was in her car found abandoned in a parking ramp at the Mall of America. Steger was co-manager at a clothing retailer, Delia's, at the mall.

Authorities allege that Trevino dropped her car off on Feb. 22. Suspected blood and Steger's DNA were found in the trunk, according to testimony.

Wright is the prosecution's last witness. He interviewed Trevino twice.

When police questioned Trevino on Feb. 24, he asked them what he should do with his wife's belongings, Wright said.

Trevino told police that the weekend before Steger went missing, she told him she was going out with girlfriends. Earlier testimony revealed that on Feb. 15 Steger stayed over at the home of a co-worker, Ryan Wendt, with whom she was having an affair.

On Feb. 17, Trevino wanted Steger to spend time with him and his friends from out of town, but she went out instead, Wright said.

Trevino seemed to vacillate between thinking that his wife was having an affair and that she wasn't, Wright testified. Trevino told police he thought the man lived in St. Louis, Mo., but subsequently learned that he lived in Maple Grove.

Wendt's Maple Grove address was found on a piece of paper in Trevino's car.

Trevino told police the last time he and Steger were physically intimate was before Christmas 2012. Wendt testified that they began their affair in January.

Prosecutors say Trevino killed Steger in a jealous rage because she was having the affair and wanted a divorce.

Steger texted Wendt at 11:44 p.m. the last day she was seen alive. Steger and Trevino had a date night just hours earlier, where they planned to discuss the future of their marriage, friends testified.

Prosecutors believe Steger was killed within about two hours of texting Wendt.

Trevino must decide by Monday if he'll take the witness stand. The tentative schedule calls for attorneys to deliver their closing arguments Tuesday morning.

The jury will be sequestered for deliberations. Six women and eight men, two of whom are alternates, have been hearing the case.

Chao Xiong • 612-270-4708 • Twitter: @ChaoStrib