A 40-year-old man suspected of fatally poisoning his mother with fentanyl at a home in San Jose was arrested this week, nearly four months after the killing, authorities announced Thursday.

The death had been under investigation since the woman's body was found around 1:20 p.m. June 6 at an East San Jose home, according to the San Jose Police Department.

The case was turned over to the Santa Clara County Coroner's Office, which determined on July 18 that the death was a homicide and that the woman had been intentionally poisoned with fentanyl.

Detectives suspected Bradley Dexter, the woman's son for a while and believed he was behind a violent attack that sent his father to the hospital with serious injuries.

On Monday, officers found Dexter in San Jose and booked him into the Santa Clara County Main Jail on suspicion of homicide, poisoning and two counts of elder abuse.

The woman's death marks the city's 28th homicide of 2023.

Homicide charges for fentanyl poisoning are rare. But the San Jose arrest comes less than a few months after a similar case around Sacramento.

In that case, a 48-year-old Elk Grove resident named Glennis Smith was jailed in July on suspicion of killing his wife, Jennifer Smith-Floyd, who died in January, according to authorities. Smith allegedly put fentanyl in his estranged wife's food on two occasions prior to her death.