Biggest cold case

“The Piketon Family Murders” takes viewers inside the largest criminal investigation in Ohio history. In 2016, police discovered eight bodies at four crime scenes, with most of the victims belonging to a single family. Hosted by attorney and TV commentator Beth Karas, the two-hour special delves into the horrific massacre that terrified residents of Piketon for more than two years until police finally arrested four suspects (who, curiously, also hail from a single extended family).

6 p.m. Sunday, Oxygen

Substituting for kicks

The producers of “Undercover Boss” take a second crack at their knee-slapper concept with “The Substitute.” This time around, they enlist the help of special effects artists, who help transform celebrities into regular-looking substitute teachers. The series kicks off with teen star Jace Norman (Nickelodeon’s “Henry Danger”) surprising a classroom of middle-schoolers.

1 p.m. Monday, Nickelodeon

Kimmel goes to Vegas

Jimmy Kimmel — aka the world’s sweetest late-night host — heads to Las Vegas for five days of live shows from the Strip. The fun kicks off Monday with appearances by the Kardashian sisters (as in: Kim, Khloe and Kourtney) and dance-rock by the Killers. Rounding out the workweek are appearances by Vegas mainstays including James Taylor, Celine Dion and Mike Tyson.

10:35 p.m., Mon.-Fri., KSTP, Ch. 5