This undated photo provided by the Lisle Police Department shows Bruce Lindahl. (Lisle Police Department via AP)

Today, as Lisle Police Detective Chris Loudon and detectives in other communities where Bruce Lindahl lived try to retrace his steps, what is emerging is a terrifying murder mystery created by a man Loudon describes as a serial killer, a monster hiding in plain sight.

(Lisle Police Department / Facebook)

A suspected serial killer strangled a suburban Chicago teenage girl in 1976 and likely killed another woman just days before she was to testify in court that he raped her, police said Monday.