In 1993, a Pennsylvania first-grade teacher named Joanne Chambers began receiving a series of hateful, threatening letters. The investigation pointed to a fellow teacher, Paula Nawrocki, who was arrested and charged [citation:2][citation:7]. However, a DNA test on saliva from the stamps of the letters revealed a shocking twist: the DNA belonged to Joanne Chambers, not her colleague [citation:3][citation:8]. The evidence suggested she had been sending the letters to herself, framing Paula in a bizarre bid for attention or to remove a disliked coworker [citation:10][citation:7].

After a day of fishing in a quiet Swiss village, a teenage boy failed to return home [citation:1]. The case seemed impossible, until forensic scientists turned to microscopic clues. Diatoms, a type of algae found in his lungs and on his sneakers, were the only evidence [citation:6]. By analyzing water samples from the region, scientists matched a specific species to the creek where his bicycle was found. This groundbreaking forensic analysis proved where the drowning occurred, leading investigators to the killer [citation:1][citation:4].

In November 1993, the small English village of Hambleton was shaken when a well-liked couple vanished without a trace. Eileen and Derrick Severs failed to show for appointments [citation:4], prompting a police investigation that would uncover a family's dark secret. Suspicion turned to their son, Roger [citation:5], who had been house-sitting while they were away [citation:4]. The breakthrough came through forensic science: careful analysis of soil and blood samples found in the couple's two cars [citation:5] led investigators not only to the bodies, but to the killer [citation:1][citation:2]. They were found hidden in woodland, wrapped in blankets [citation:4], and Roger eventually confessed to the murders of his parents [citation:4][citation:5].

When a Pennsylvania electrician checks into the hospital with severe leg pain, doctors initially diagnose him with a rare neurological disorder. But as his condition rapidly deteriorates and his hair falls out, a physician recognizes the telltale signs of thallium poisoning. Investigators soon discover the poison was in his thermos, and the trail leads to a chilling motive: his wife was waiting to collect a massive life insurance payout. A segmental hair analysis proves he was poisoned over a long period, exposing a cold, calculated murder motivated by greed.

A 40-minute jog. A wife face-down in a hotel bathtub. A death that looked like a tragic accident. 
Ed Post's story began to unravel when investigators discovered a $700,000 life insurance policy and a second autopsy revealed 36 bruises the first one missed. 
A broken towel ring that couldn't have been broken in a fall became the key piece of evidence.
In 1986, Edward Post left the Omni Hotel in St. Louis for a jog, leaving his wife Julie in a drawn bath[reference:0]. He returned to find her unresponsive, and she was pronounced dead shortly after[reference:1]. The initial autopsy ruled it an accidental drowning, but investigators grew suspicious of Ed's story[reference:2]. They discovered a $700,000 life insurance policy he had taken out on her[reference:3]. A second autopsy found 36 bruises not noted in the original exam[reference:4]. A forensic test on a broken towel ring contradicted Ed's claim that Julie had pulled it during a fall[reference:5]. Ed was convicted of first-degree murder and later admitted to drowning his wife[reference:6].

In 1983, a serial killer stalked Nebraska, binding and murdering two young boys. A unique "junk rope" and an FBI profile were the keys to stopping him. The investigation, which used rope analysis and hypnosis, led to John Joubert, an Air Force enlistee who later confessed to another murder in Maine. In a separate case, a North Carolina gas station clerk was shot dead during a robbery by two brothers. This episode of Forensic Files reveals the crucial forensic evidence that brought these killers to justice.

A beloved teacher who devoted her life to troubled students answered a knock at her door. A 15‑year‑old girl she trusted asked to use the phone. The night ended in a field with a gunshot. When Diane Tilley vanished, police found her home ransacked and a bullet hole in her couch. ATM footage showed a young girl and a man using her card. The investigation revealed a father who used his own daughter to commit a brutal robbery and murder. A single shoelace stolen from the victim's home helped seal his fate.

A 911 call in the dead of night. Two young boys stabbed to death. A mother with a wound on her neck. Darlie Routier claimed a crazed intruder attacked her family. But the crime scene told a different story. Blood spatter, behavioral profiling, and a chilling 911 call exposed the truth. The evidence proved she killed her sons, inflicted her own wound, and staged the scene[reference:0][reference:1]. She was convicted of first-degree murder and sentenced to death[reference:2]. This is the case of an invisible intruder who never existed.

In a quiet English village, a farmer discovers a severed lamb's head impaled on his fence with a chilling note: "You next." A car bomb nearly kills his wife, and a neighbor is shot dead in a supposed home invasion. But forensic science reveals the farmer's story is a web of lies — manipulated crime scenes, fabricated threats, and a motive as old as greed. He staged everything to collect his wife's life insurance. This is the bloody trail of a farmer who turned his life into a deadly plot.

In 1971, a quiet New Jersey mansion became a tomb. A devout accountant murdered his entire family, left a confession, and vanished. For eighteen years, he built a new life under a stolen name. But justice never forgot. Using an age-progressed forensic bust and a tip from America's Most Wanted, investigators finally tracked him down. This is the story of a family annihilator who thought he could outrun the law—and the art and science that brought him back.