After a public health nurse vanishes without a trace, Anchorage, Alaska, investigators get a major break from her terrified neighbor; the race is on to recover evidence before it disappears under Alaska's winter snow. [also shown as S6:E7]

When the body of a single mother turns up in a snowbank outside Anchorage, Alaska, the evidence points to the victim's fugitive fiancé; the shocking murder of a second native Alaskan sparks investigators' fears that a serial killer is on the loose. [also shown as S6:E8]

A killer stabs a beloved New Jersey woman 44 times in her home. Investigators have the culprit's DNA, but finding him will require an assist from the FBI, a media blitz and a random tip with details only the murderer would know. [also shown as S6:E9]

Niagara Falls detectives find 72-year-old real estate agent Bruce Firman bludgeoned to death with a pipe wrench in the home he shares with his estranged soon-to-be ex-wife; Bruce was also a serial monogamist with a long list of jilted ex-lovers. [also shown as S6:E10]

An enraged killer strikes down 26-year-old Alexandra Ducsay, an aspiring entertainer with a big heart and a blossoming career; slain inside her family's Connecticut home, her attacker uses her own dance trophy to bludgeon her to death. [also shown as S6:E11]

A late-night break-in at a Pennsylvania chain restaurant leaves assistant manager Terri Brooks brutally slain; when another female restaurant employee is murdered in a nearby town, detectives fear there's a serial killer on the loose. [also shown as S6:E12]

A shooter guns down Cleveland's beloved fire department lieutenant on his driveway; as he fades away, 45-year-old William Walker tells the EMS as much as he can about the suspect who ambushed him. [also shown as S6:E13]