TL;DR: “20/20” kicks off its new season tonight, Friday, Sept. 25, at 9 p.m. ET on ABC with “The Salem Strangler,” a two-hour investigation into the 1986 murder of Salem State student Claire Gravel.

After more than 30 years, DNA leads investigators to a suspect. But that man can't be charged due to statute of limitations laws that the victim says need to change.