WAUKEGAN, IL (STMW) — A Cook County Sheriff’s deputy who dated Marni Yang said he helped her train to use guns and often took her to a shooting range for target practice, and said she gave him two books on how to make gun silencers.

But Salvador Devera said he didn’t know Yang was having a relationship with former Chicago Bear Shaun Gayle, that she claimed one of her guns went missing or that his credit card was used to rent a car the day before Rhoni Reuter was killed, he testified in court Wednesday.

Lake County prosecutors say Yang, now 43, developed an obsession with Gayle and gunned down his pregnant girlfriend in her Deerfield home. They called on Devera to testify to set up their attack on Yang’s alibi later in the trial.

Devera, a court services deputy, said he met Yang in 2002 at a bar where she worked. They dated until the end of 2007, during which time they frequently visited Illinois Gun Works in Elmwood Park for target practice.

Devera said Yang was not familiar with guns when they first met, but she obtained a Firearm Owner’s Identification card so she could go to the shooting range with him.

She collected as many as four handguns, including two she inherited from a deceased uncle, but never told Devera one went missing, as she later told police investigating Reuter’s murder, he said.

In a later interrogation, Yang eventually told detectives that a 9mm Beretta was stolen from her home a few weeks before the murder, around the same time a camera and video game system went missing. The gun that killed Reuter was a 9mm, witnesses testified Monday.

Jurors may not hear Yang’s story of the missing gun, though. Judge Christopher Stride ruled the January 2008 interrogation tapes inadmissible because she asked to call her attorney at the start.

Devera said Yang never told him about one of her guns being stolen, an omission he called “a big deal.”

“A missing gun would be bigger thing to worry about than a missing camera or missing game system,” he said.

Devera also testified to helping Yang buy a new car battery during his lunch break on Oct. 4, 2007 — a few hours after Reuter was killed. Prosecutors allege Yang staged her car problems as an alibi and an excuse for not showing up for work the day of the murder.

Devera also said he did not recognize an Enterprise Rent-A-Car receipt showing his credit card used to rent a car on Oct. 3, 2007. Authorities contend Yang rented the car to carry out the murder.

Prosecutors on Monday spent time going over evidence that Yang had bought two books on how to make silencers — and some of the materials needed to do so. On Wednesday, Devera said Yang gave him the two-volume set, “How to Make Disposable Silencers,” as a birthday gift about two weeks before Reuter’s death.

He said he “was upset” because both he and Yang were low on cash at the time and the gift was “useless.” After an argument, Devera said he left Yang’s house without the books and never saw them again.

Devera said he had always suspected Yang had developed a relationship with Gayle. The former football player confirmed that for the first time when he took the stand Tuesday, testifying that he and Yang had sex the evening before Reuter was killed.

“I suspected she had been cheating on me for a while,” Devera said. “It was just a feeling I had. Her children hinted at me that she might be going behind my back.”

Devera and Yang were working security together at a Bears convention in 2005 when they met Gayle.

“I suspected Shaun Gayle” was the other man, Devera said. “It appeared to me he had an eye for her. He had taken a liking to her.”

Expected to testify Thursday is Christi Paschen, a friend of Yang who cooperated with police to implicate herself in Reuter’s murder. Prosecutors plan to play wiretap recordings of Yang and Paschen discussing Reuter’s death in court as well.

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