A Michigan man accused of killing his wife by spiking her cereal with heroin allegedly bought anxiety drugs from a co-worker, telling him he planned to crush them up and give them to his spouse “so she would stop nagging him,” a witness reportedly said in court Tuesday.

Jason Harris, 44, has pleaded not guilty to first-degree murder, solicitation of murder, and delivery of a controlled substance after his August arrest for allegedly murdering his 36-year-old wife, Christina Ann-Thompson Harris, in 2014. If convicted, he faces a maximum penalty of life in prison.

The Genesee County Medical Examiner initially ruled Christina’s death an accidental heroin overdose—despite claims from her family that she was never a drug user. But in 2016, a Michigan State Police crime lab tested three packages of the mother of two’s frozen breast milk and found no previous traces of heroin. Her death certificate was amended in August to indicate she died of a homicide.

During a preliminary hearing Tuesday, several witnesses testified about Harris’ alleged plans to murder his wife and recalled the morning of the incident.

David Groshon, a former co-worker at United Plastics, testified on Tuesday he sold Harris Xanax and Klonopin, alleging the 44-year-old said “he was going to crush up the pills to give to his wife so she would stop nagging him.”

Groshon added that Harris later told him his wife tasted the pills, which he’d plan to put in her milk or water, according to WNEM.

Authorities said on Sept. 29, 2014, neighbors found Christina unresponsive in the master bedroom of her Davison home. One of the neighbors testified on Tuesday that she found Christina lying on the bed without a pulse and with “foam coming out of her mouth.”

At the time, Harris told police his wife had been suffering from a cold and called a neighbor at around 10 a.m. to check on her while he was at work.

“She, the neighbor, thought that was unusual,” Genesee County Prosecutor David Leyton said in August.

Prosecutors allege Harris put heroin into his wife’s cereal and milk the night before, believing the drug was undetectable after “multiple” conversations with his co-workers. During a deposition for a wrongful death lawsuit filed by Christina’s family after her death, Harris told authorities he made his wife the late-night snack at her request.

“She got hungry. I made her up a bowl of cereal. That's what she asked for. I know she was sitting in the chair, dropped the spoon,” Harris said, adding that his wife fell asleep while pumping milk for their newborn daughter.

The case remained untouched until October 2014, prosecutors said, when Harris’ siblings reported to local police that Jason had previously made remarks about “getting rid of Christina” and had been seeing other women just before her death.

Harris admitted in the deposition that his wife knew he had sent “sexual messages” to another woman—including one from Rhode Island who moved into his house with her child just weeks after his wife’s death.

The woman was reportedly still living with the 44-year-old at the time of his arrest.

The 44-year-old’s co-workers also told investigators Harris admitted he “just needed to get rid of” his wife of 11 years so he wouldn’t have to deal with a divorce, child support payments, or a custody battle. Instead, Harris allegedly asked a colleague to kill Christina for $5,000, admitted to spiking his wife’s water with Xanax pills, and polled the office on which pills were “odorless and tasteless.”

“Jason paid $5,000 to a guy to kill Christina and while this alleged hit man was doing surveillance on her the hit man was caught by police with a firearm,” Genesee County Prosecutor David Leyton said in August.

Leyton added the failed murder attempt prompted Harris’ quest for an undetectable fatal drug, allegedly making Christina suspicious enough to confide in a friend.

“She told a friend that if something happens to me, look at Jason,” he said.

In the deposition, Harris told investigators he received about $150,000 from his wife’s life insurance—which he used to pay off his student loans. A Legacy.com obituary for Christina also directs memorial contributions to be made out to Jason “in lieu of flowers.”

Harris is expected to return to court on Nov. 5.