A Pennsylvania Sunday school teacher is executed in a sniper-style attack.

A young woman is found floating in a river off Merritt Island, east of Orlando, Florida. And as the circumstantial evidence piles up, the shifting story of one suspects' timeline ultimately becomes the smoking gun.

Fifteen-year-old twin girls make a horrific after-school discovery when they come home to find their mother floating dead in the bathtub. Their compelling testimony leads the investigation, but the hair-raising truth lies hidden in the details.

Searching for a dismembered New Hampshire woman's killer, police identify a series of potential suspects including a mysterious drifter named Razor. But the truth lies in a missing persons report, and a one-eyed teddy bear.

A Jacksonville firefighter discovers his wife's lifeless body in the bedroom of their home. His confession of infidelity initially makes him the prime suspect. But it's a stolen car caught on CCTV that ultimately leads investigators to the killer.

A double homicide in New York City soon becomes a media circus when investigators reveal the two victims led a secret life; as the list of suspects grows, it's a call from the victims' home that may provide the only link to the killer.

A tight-knit Georgia community is in shock when a 41-year-old woman is bludgeoned to death in her own home. As detectives look to piece together her final hours, a story from behind bars reveals the shocking motive for murder.

In an affluent Atlanta suburb, a young boy is stabbed 18 times when he returns home from school, and his mother's lifeless body is discovered in her bedroom; a neighbor's chilling story points police toward a psychopath.

When an 18-year-old Staten Island woman is murdered in her home, the media turns her secret into a front-page scandal. But a meticulously constructed timeline allows detectives to close in on their number one suspect.

The investigation into a Florida woman's murder takes a bizarre turn when an out-of-state tip about a homicidal hitchhiker. But the smoking gun comes via a local pawnshop, revealing a killer who lurks dangerously close to home.

Georgia detectives investigate the timeline of a family involved in a triple shooting find motive in both their failing business and a local addict with a grudge. But the discovery of a hidden key ultimately unlocks the secret to the killer's identity.

Confessed fraudster Andrew Kissel is found stabbed to death in the basement of his rented Greenwich, Connecticut home. And in order to find the killer detectives must unravel every detail of his last 24 hours.

When Diane Holik's body is discovered in her Texas home, detectives are faced with one of the most pristine crime scenes they've ever encountered; they unearth multiple suspects, but only the victim's reconstructed timeline can identify the killer.

When a Louisiana man is shot in his sleep, detectives uncover details of his extracurricular love life and a death policy that promised to pay out, even in the event of his murder.

Amid rumors of buried treasure at a Louisiana pet cemetery, the property's reclusive owner is found wrapped in heavy chains at the bottom of a river. Somebody wanted her to disappear, but it will take over 20 years before police can find her killer.

After Genore Guillory is brutally murdered in her own home, investigators look at several suspects on the woman's final 24-hour timeline; unable to pin anyone down, the case goes cold, until a witness comes forward with the inside story.

When firefighters in Arlington, Texas extinguish the flames of an apartment fire, they discover the charred remains of 19-year-old Missy Grubaugh. Several of her restaurant coworkers soon come under scrutiny.

When a nursing student is shot dead outside a Houston community college, the search is on for a brazen shooter in a red car. Detectives retrace the last 24 hours of the victim's life, and unearth a number of potential suspects.

The body of a 16-year-old high school cheerleader is found floating in a river bordering Texas and Oklahoma; the police investigation unearths several promising suspects, then a break points to a killer already in their midst.

Popular newlyweds Rick and Gail Brink are shot execution-style in their Michigan home. But it will take 25 years before investigators uncover a flaw in the timeline that convinces them of the killer's guilt.

A man comes home to find his fiancée dead in the bedroom of their new home; the discovery of infidelity soon puts him firmly in the hot seat; as investigators piece together the victim's final 24 hours, they uncover a sinister plot.

In rural Michigan, 34-year-old Deborah Boothby is run over on the highway, and for nine years the case goes unsolved. That is, until a team of detectives review the evidence and the hit-and-run cold case becomes a murder investigation.

Sixteen-year-old Theresa Burns is brutally murdered in her family's Indiana home; though investigators believe they've found the murder weapon, it will take a quarter of a century before they close in on the killer.

When a woman is murdered in her Alabama home, investigators receive a lead pointing to a high-profile suspect, but it will take a decade before their circumstantial murder case has enough substance to go to trial.

A successful vacuum salesman is gunned down outside his Indiana office; as detectives untangle the victims' final 24 hours, all the clues point to a hired hit.