Season 4

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.

John is in pursuit of suspect Jonathan Dorado, wanted for killing a woman and her unborn child in an act of misplaced gang revenge; Cal hunts for Henry Houston, accused of conning a vulnerable woman and later killing her father in an altercation.

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 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 girl goes missing after a night out in Vegas, police suspect her friend Erick Rangel-Ibarra; Cal goes after Jerold Dunning, accused of sexually abusing his girlfriend's daughter for years.

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.

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 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 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 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.

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.

John hunts for Jose Bustos-Diaz, a convicted killer and prison escapee suspected in another slaying. Later, Cal's in pursuit of Benjamin Williams, accused of murdering his ex-girlfriend in front of her two young children, including his own baby.