When a man is senselessly gunned down at a party, police learn it may be a case of mistaken identity; John joins the hunt for suspect Colin Jerrick; Cal helps police hunt David Bonness, accused of sexually abusing his former stepdaughter.

John joins law enforcement in pursuit of Luis Montes, accused of murdering his on-again-off-again girlfriend in Texas; Callahan heads to Chicago to shine a light on two victims of gun violence whose cases remain unsolved.

John is in pursuit of William Strand -- police say he killed his ex-girlfriend who was also the mother of his son. Later, Cal hunts for Leslie Lagrotta, a suspect accused of sexually assaulting women in central Florida for over a decade.

Luis Frias makes John Walsh's most-wanted list after allegedly stabbing his common-law wife to death in front of their children; Callahan Walsh explores the case of Harold Butch Knight, who left a trail of clues after confessing to killing his wife.

John joins the search for Celina Mays, whose disappearance draws police attention to her family-run, allegedly cult-like church; Cal hunts for Efren Meza, who was accused of stalking and stabbing his ex-girlfriend.

When a young father is executed, police learn the shooter may have been his close childhood friend. John helps track down the alleged killer, Diontae Whitson. Later, Cal's in pursuit of Louis Rojas, accused of murdering his ex-wife's new husband.

John is in pursuit of Jolene Hibbs and Charles Ausiello, a couple accused of murdering a retiree and selling off his assets; John and Cal team up to hunt for the mysterious Boca Raton Mall murderer who terrified South Florida in 2007.

Salvador Vaca Garcia tearfully appears on local news when his girlfriend vanishes. John Walsh scrutinizes Garcia's story. Later, Callahan Walsh looks at Brian Keith Freeman who allegedly killed his fiancé when their engagement fell apart.

John joins the hunt for Arturo Munguia, aka Jesse Vega, accused of murdering his girlfriend in an act of petty jealousy. Later, Cal helps track down Rex Byrnes, an unemployed metalhead whose own daughter accuses him of years of sexual abuse.

John Walsh explores the case of conman Edgardo Perez who allegedly preyed on older men until it turned deadly. Callahan Walsh heads to Boulder where teenage babysitter Chris Deininger confessed to abusing 29 kids in his care before fleeing.

John Walsh investigates how Eric Jones, the son of a preacher, allegedly turned to murder. Later, Callahan Walsh tries to make sense of how a dispute over a dog could provoke Ricardo Villanueva Cordova to reportedly commit murder in broad daylight.

John Walsh profiles Mike Bullinger's secret double life that police believe ended in a triple homicide. Callahan Walsh looks at the case of Tomas Magallon Gonzalez, who allegedly abused his stepdaughter for years before taking her life.

John helps police track down Glen Holmes, accused of carjacking a couple and murdering one of them. Later, Cal joins the hunt for online predator Adrian Fierros, who coerces young girls into sending him explicit photos that he uses to extort them.

John Walsh investigates a whirlwind romance and the accusation that Lamont Stephenson strangled his fiancé and her dog. Callahan Walsh explores claims that Gloria Schulze is a freeloader drunk driver who repeatedly cheats the legal system.

John Walsh profiles Juan Lazaro Abrego who is believed to have murdered his ex-girlfriend, a beloved teacher. Callahan Walsh investigates Derek Dean, a St. Louis man accused of shooting a pair of twins, killing one and wounding the other.

John Walsh follows the story of Glen Stark Chambers, who killed his girlfriend and then escaped prison (not once but twice); Callahan Walsh follows Jesus Salazar, a suspect of murder who eludes capture for decades.

John goes after Eduardo Clemente, the prime suspect in his girlfriend's murder after her body turns up in the desert; Cal visits North Carolina to hunt down Emigdio Ramirez Garcia, accused of ruthlessly murdering his wife in 1997.

John hunts Omar Cardenas, the prime suspect in the murder of a devoted father who may have been caught in a random act of gang retaliation. Later, Cal heads to Pennsylvania to track Justin Smith, accused of murdering his pregnant girlfriend.