DENVER (AP) — The death of a Colorado woman reported missing on Mother’s Day nearly four years ago was a homicide, authorities said Monday, revealing new details in a case that at one point led to murder charges against her husband that were later dropped.

Suzanne Morphew died by “undetermined means,” according to an autopsy report released by the Chaffee County Attorney’s Office. A cocktail of drugs that are used to tranquilize wildlife was found in one of the 49-year-old woman’s bones but there was no indication of trauma, the report said.

Morphew’s husband, Barry Morphew, told investigators he last saw his wife in May 2020, on Mother’s Day. Her remains were found in September 2023 in a remote area of central Colorado more than 40 miles (65 kilometers) south of her home.

A tranquilizer gun and accessories were found in the couple’s home, according to investigators, who arrested Barry Morphew in May 2021 on suspicion of first-degree murder, tampering with a human body and other offenses.