Jason Harris, 44, was taken into custody on suspicion of first-degree premeditated murder, solicitation of murder and delivery of a controlled substance causing death, WJRT-TV reported. Christina Ann-Thompson Harris died in her home on Sept. 29, 2014 in Davidson, a city 11 miles east of Flint.
“We believe Jason Harris murdered his wife," Genesee County Prosecutor David Leyton said at a news conference. “We believe he put heroin into her cereal and milk the night that she died after getting it from someone, thinking it would be tasteless and odorless."
Investigators said Harris tried to hire a hitman to kill his 36-year-old wife, but eventually settled on poisoning her. He allegedly fed her the tainted cereal the night before she died.
She had given birth to the couple's second child weeks before.
The Genesee County Medical Examiner's Office initially ruled the death an accidental heroin overdose. Leyton said packages of breast milk made by the wife before she died showed no traces of heroin.
He said it proved she ingested the drug in a short amount of time and was not a regular user, the news station reported.
Officials changed her cause of death last week to homicide. Leyton said Harris' siblings told police he talked about "getting rid" of his wife.
Co-workers told investigators that Harris had been looking for a hitman as well.
He appeared in court Tuesday and was denied bond. It wasn't immediately known if he had an attorney who could comment.
The Associated Press contributed to this report.