When a fisherman finds evidence of a young girl's death washed up on a shore in New Jersey, Lilly re-opens the 1965 case of 4-year-old child who had a seemingly abusive mother.

The headless torso of a woman who disappeared in 1985, on the same day she filed domestic-abuse charges against her husband, is found by hikers in a wildlife preserve. The investigation quickly leads to the grisly discovery of 8 more decapitated bodies, the victims of a serial killer.

The 1994 case of a raped and murdered 16-year-old girl is re-opened when Det. Jeffries gets a call from a prisoner on death-row -- scheduled to be executed in just three days.

The team re-investigates the 1968 death of a policeman who was shot in his patrol car. The case was then ruled as a drug bust gone bad, but new evidence now reveals the victim may have been romantically involved with his partner.

When an old truck containing human bones is pulled from the Delaware River, the team re-opens the case of a missing and possibly murdered girl who disappeared unexpectedly in 1932.

The discovery of nine human skulls leads Rush (Kathryn Morris) back to George Marks, the serial killer she was unable to incriminate months earlier, and who walked away a free man. As the detectives reinvestigate his mother's murder from 1972, George is forced to emerge from hiding to face Rush again. This time, their very lives are at stake in their final showdown.

Lilly investigates a 1995 shooting spree at a mall in which two teen boys killed 15 people before committing suicide. The case is reopened when a video of the crimes is found and it suggests that a third shooter was involved. Elsewhere, Stillman asks Valens to investigate whether Valens' brother may have been molested by a boxing coach in the 1980s.

The 1975 disappearance of an 8-year-old girl who was never found is reinvestigated after a note written by the girl shortly before she vanished turns up. Their friendship rattled many in the predominantly white neighborhood and the girls quickly became targets of hatred.

Lilly investigates the case of Daniel Holtz, a college baseball player who was found beaten to death in an alley behind a gay bar in 1964. Daniel's mother comes to Lilly in the hopes that his killer can be brought to justice before she dies. Lilly discovers the maltreatment gay victims received in the 60's, when her investigation discloses that it may have been a policeman's nightstick that made the lethal blows.

Lilly reopens a 1990 murder case, in which a prep-school girl was found dead in a local swimming hole, after a present-day victim with similar markings is discovered at the same place. The investigation reveals that the victim of the earlier crime was routinely tormented by a trio of classmates who invited her to a sleepover the night she was killed.

The unsolved 1963 murder of a black teenager, whose body was discovered by the then-young Will Jeffries, is reopened.

When a body is found in a dumpster, the team re-opens the 1984 case of a murdered teenage boy who wanted to become a dancer against his father's wishes.

The team re-opens the 1963 case of teenage girl who was then thought to have committed suicide. Now, new evidence leads them to believe the girl might have been murdered for acting and dressing like a boy.

Rush and Valens re-open the case of a 25-year-old black woman, who was murdered in 1939, after the woman's granddaughter comes forward with new information. The woman was assumed to be a prostitute murdered by a client, but letters written by the victim indicate that she was afraid of a milkman.

Lilly and Valens reopen a presumed homicide from 1979 in which an unidentified victim's blood-drenched shoes, underwear and sheets were found in a trash bag, but no body. The investigation begins when a battered wife accuses her husband of murdering a girl in 1979 and brings in an amateur film from the time that supposedly shows him committing the crime.

Lilly investigates the 1993 death of a mentally challenged teen who was hit by a train, after drawings appear on his grave that indicate foul play might have been involved.

In the fourth season finale, a hostage situation arises when the entire team is held captive while they're investigating the 2006 killings of a family who had just moved into a new house.

The team re-investigates the suspected 2007 murder of a bride-to-be who was kidnapped on the day of her engagement party. Lilly and Scotty travel to West Virginia to escort the prime suspect to Philly, and on their way back, they hear his side of the story.

Realizing that the missing Vera has finally hit rock bottom, his worried team members hope that a new twist to a 2006 arson case, which he was secretly obsessing about in recent weeks, might supply leads to his whereabouts.

When a young woman, Rosie, wakes up from a coma, Lilly re-opens the fall in which her 6-year-old daughter Toya died. Things get complicated when the mother remembers very little of that night, and Lilly feels especially motivated to find the killer.

The 1958 death of an unknown 6-year-old boy found in a field inside a cardboard box is reinvestigated after a small suitcase with the child's picture and his old cowboy hat is left in front of a church. The new probe reveals that the rowdy boy lived at a Catholic-run orphanage and was adopted two days before his suspicious demise.

Lilly re-opens a 2003 case in which an autistic boy's parents were shot in their car when Joseph brings her information that the boy might have seen the killer.

After traces of blood linked back to a missing teen are found, the team re-investigates the 2006 case of a boy who disappeared from a high school for deaf children.

The team has to cope with their own emotions as they search for the shooter responsible for Jeffries' shooting.

After determining the serial killer's identity - and some of his likely future targets - the team and the FBI work together to apprehend him while trying to locate and protect the people he's preparing to kill.