Police said Tuesday they have charged Geoffrey Michael Campbell with first-degree murder in the death of his 16-year-old girlfriend, Maribeth Williams, the Windsor Star reported Wednesday. Campbell is already serving a prison sentence for manslaughter in another case, the newspaper said.

Campbell allegedly killed Williams in her apartment and left her crying infant son with her body.

"The murder of anyone is taken very seriously," Inspector Greg Renaud said. "But the strangulation murder of a young 16-year-old girl inside her home, and the cold nature of the homicide was certainly troubling to the police service and to many members of the community. To leave an infant in a crib unattended with no assistance whatsoever takes a certain type of very cold individual."

Brampton Superior Court Justice Casey Hill called him a "pure psychopath" who commits violent crime "simply for the thrill of it."