Serial killers try their best to hide their true nature from the outside world.

They hide in plain sight looking just as normal as the next person. They are difficult to track down because they rarely leave any evidence behind and are long gone from the crime scene by the time authorities arrive. But thanks to modern forensics, a number of them have been identified and apprehended before they can further commit cold-blooded murders.

Here are some serial killers whose trails of terror have been stopped by forensic science:

Joseph DeAngelo

Dubbed as the Golden State Killer, Joseph DeAngelo committed a string of murders and sexual assaults across northern California dating back to the 1970’s. His experience as a former police officer helped him elude authorities for more than 40 years as he knew about evidence collection and was careful not to leave any. He’s been linked to at least 13 murders and more than 50 rapes from Sacramento to San Francisco to Los Angeles.

He came under scrutiny after the DNA from the crime scenes was linked to familial DNA found in an open-source genealogy website. There was an exact match between the crime scene sample and the DNA profile stored in GEDmatch, a public ancestry database used by people researching their family trees. His arrest is the first known case of law enforcement successfully using this modern DNA technique.

Albert Fish

Small, quiet, and unassuming, Hamilton Howard “Albert” Fish was a serial killer, child rapist and cannibal who admitted to molesting more than 400 children during a span of 20 years. Known as the “real-life Hannibal Lecter”, he smilingly described to police the horrific details of the tortures and murders he committed including making “a stew out of (a victim’s) ears—nose—pieces of his face and belly.

His most sensational murder was the kidnapping and butchery of 10-year-old Grace Budd which the police investigated for 6 years. They were about to give up hope when Fish send an anonymous letter to Grace’s mother detailing how he strangled, cut into pieces and eaten the young girl. Detectives used the handwriting on the letter and the stationary form to track him down and send him to the electric chair.

James B. Grinder

For 15 years, James B. Grinder was the primary suspect in the rape and murder of Julie Helton who was reported missing and later found stabbed and beaten to death near the railroad tracks in Macon, Missouri. There just wasn’t enough evidence to bring him to trial as he gave several different, contradictory accounts of his involvement.

Finally, authorities turn to brain fingerprinting technology which showed that Grinder’s brain has stored certain salient features of the crime only the perpetrator would know like the murder weapon used, the specific method of killing the victim, the specific injuries inflicted on her, and the items taken during the crime. Grinder confessed and later pled guilty to the murders of three other teenage girls.

H.H. Holmes

Born into a wealthy family and interested in medicine, Herman Webster Mudgett enrolled in medical school, passed his medical exams, and worked at a pharmacy under the alias Dr. Henry H. Holmes. He built a hotel across the street where he lured guests for asphyxiation, dissection, incineration or dissolution in vats of acid.

He killed his business partner Ben Pitezel as part of an insurance fraud scheme along with three of the victim’s five children as well. Holmes was eventually convicted with the evidentiary bones and teeth of Pitezel found in the chimney of a cottage the doctor had rented. He later confessed to 27 other murders though missing person’s reports suggest the actual count could number into the 100s.

Jerry “Animal” McFadden

Calling himself the “Animal,” Jerry Walter McFadden raped and strangled an eighteen-year old girl and murdered two teenagers during a daylong rampage in 1986. He was the target of the biggest fugitive hunt in Texas state history after escaping from jail and taking a female corrections officer hostage. He was recaptured and later executed by lethal injection in 1999.

Thought to be solely operating in the Lone Star state, McFadden actually traveled to the Pacific Northwest at the time when twenty-year-old Anne Marie Hlavka was strangled and sexually assaulted in Portland, Oregon. The intact DNA saved from under Anna Marie’s fingernails matches that of McFadden’s found in a public genealogy database to solve the nearly 40-year-old cold case.

Dennis Rader

A pillar in his Wichita, Kansas community with a wife and two children, Dennis Rader lived a remarkably normal looking outward life as a church council president and family man. No one suspected, not even his wife, that he was actually the self-named BTK (Bind, Torture, Kill) Killer who tortured and murdered 10 people for almost two decades.

Between the semen evidence at the crime scenes that matched his daughter’s DNA, the handwriting on the taunting letters he sent to authorities and the floppy disk he sent to a TV affiliate with metadata embedded in it, Rader was charged with 10 counts of first-degree murder, pleaded guilty to all of the charges and is currently serving 10 life sentences.

Harvey Robinson

At the age of 17, Harvey Robinson attacked five women raping four of them and killing three in a span of one year. He stalked his victims, broke into their homes when they were alone, and raped, beat and murdered them usually by stabbing or strangulation. Survivors were stalked again until they were vulnerable to a new attack.

Realizing that he would not stop until a survivor was finally dead, police assigned an officer to stay at a victim’s house where sure enough, Robinson appeared to finish the job and was wounded during the ensuing shootout. The blood samples and hair collected from one of the dead victims matched Robinson’s DNA forming a solid case that found him guilty of rape and murder. He is now in death row while sentenced to a combined 97 years in prison.