The man who killed a Black Forest girl in 1991 has been tied to at least 19 other homicides in nine states and overseas by statements he made to the El Paso County Sheriff’s Office, making him one of the more prolific serial killers in the nation.

Robert Charles Browne, 53, who’s serving life without parole in a state prison in Cañon City for the kidnapping and murder of 13-year-old Heather Dawn Church, pleaded guilty today in El Paso County District Court to one of those additional killings: Rocio Sperry, the wife of a soldier and mother of a 3-month-old girl, whose strangled body Browne said he put in a Colorado Springs trash bin in 1987. Her body was never found.

Browne pleaded guilty to the murder in exchange for a concurrent life sentence, and has told authorities he’s killed 48 people.