How Many Did He Kill? The Mystery of Convicted Killer Mark Riebe

July 17, 2018
By: Matt Gilligan

Photo by: Mark Riebe [Florida Department of Corrections]

Mark Riebe [Florida Department of Corrections]

Florida has seen its share of serial killers throughout the years. Ottis Toole, Ted Bundy, and “the Gainesville Ripper” Danny Rolling all terrorized The Sunshine State, the specifics of their appalling crimes well-known from various books and documentaries. But in the case of convicted murderer Mark Riebe, it’s what investigators and the public don’t know about his crimes that gives him an air of mystery and terror.

Prosecutors and police in Florida are certain that Riebe committed one murder, but there are suspicions that he may be responsible for many more deaths and that he might, in fact, be one of the worst serial killers in the state’s history.

From the late 1970s until the early 1990s, it is believed that Mark Riebe used Florida’s Panhandle as his own personal hunting ground. Women mysteriously vanished into thin air, some turning up in shallow graves, and others never found at all.

The lone murder that police know for sure that Mark Riebe committed occurred in August 1989. Donna Callahan, 29 and pregnant, disappeared from her job as a convenience store clerk in Gulf Breeze, Florida, near Pensacola. There were no signs of a struggle, and Callahan left behind her car, purse, and keys.

Photo by: William Wells [Florida Department of Corrections]

William Wells [Florida Department of Corrections]

It would take several years, but investigators later learned that Mark Riebe and his half-brother William Alex Wells abducted Callahan that night, and Riebe strangled the young woman to death in the backseat of a car as she begged for her life and the life of her unborn child.

It wasn’t until July 1996, nearly seven years after her murder, that Donna Callahan’s friends and family learned the details of the terrible tragedy that took place. It was then that Wells led police to Callahan’s buried remains on a farm in De Funiak Springs, Florida — a rural area northeast of where she’d been abducted. Wells was serving a 30-year sentence for robbery when a fellow inmate snitched to authorities that Wells was involved in the slaying.

Wells cooperated with police to avoid the death penalty and implicated Mark Riebe in the crime. Riebe was convicted and received a life sentence in May 1998 for the murder of Donna Callahan. Wells received a life sentence as well. Both men were locked away for good, but that wasn’t the end of the story.

After Riebe began his sentence in a Florida penitentiary, he provided investigators with chilling insight into the mind of a violent killer. Riebe was only behind bars for two months when he began to talk. He confessed to 12 killings in addition to the murder of Donna Callahan, providing gruesome details that only the the killer would know. And then, suddenly, Riebe recanted his confessions. Did authorities have another Henry Lee Lucas on their hands, a serial confessor seeking attention from the press? Despite going back on his confessions, the police believed that Riebe was a bonafide serial killer and was responsible for many more murders.

The earliest case Riebe is suspected in occurred when he was only 17-years-old. Bonnie Gayle Ryther was a 27-year-old cocktail waitress who disappeared after leaving a bar in Fort Walton Beach in April 1978. Ryther was missing for a week before her battered body was found in some woods about 30 feet from where her Ford Pinto had been abandoned. Riebe went out of his way to tell investigators what kind of beer Ryther liked to drink. Cans of that brand were found near her body.

Riebe also confessed (and, again, later recanted) to the abduction and murder of Jaqueline Brant, an 18-year-old from Illinois who was in Panama City Beach for Spring Break in April 1986. Brant’s body was found seven months later in a wooded area by a hunter. A law-enforcement official who investigated the crime and interviewed Riebe said, “He knows several things that only the killer would know.”

Another cold case that Riebe has confessed to was the 1990 murder of Ronda Taylor. The 23-year-old woman had been stabbed to death and her body was left in the backseat of her car in Fort Walton Beach.

The disappearance of 36-year-old Pamela June Ray is yet another case that investigators think Riebe was involved in, along with his half-brother Wells. Ray disappeared from a motel parking lot in Panama City Beach on August 12, 1992. Her car was discovered in the motel parking lot with the keys locked inside and her two children sleeping in the vehicle.

Ray had arrived from Georgia in the middle of the night and was walking around the motel parking lot until a room became available. Witnesses told police that they saw a man follow Ray to the motel pool and then heard screams. Pamela June Ray has never been seen since. In 2000, cadaver dogs were brought in to search the same, isolated area where Donna Callahan’s remains were discovered, but so far there has been no trace of Ray. Mark Riebe confessed to Ray’s murder, but, as he would over and over again, later denied any involvement in the woman’s vanishing.

Since Mark Riebe began his life sentence, he has repeated a pattern of confessing, recanting, and denying any knowledge of unsolved murders throughout Florida’s Panhandle. Today, 57-year-old Mark Riebe languishes in the Blackwater River Correctional Facility in Florida’s Panhandle.

Will Riebe confess to more murders behind bars and give the loved ones of the victims closure? Or will he continue to play a game of cat-and-mouse and confess and recant as he’s done in the past? One thing is for certain: Mark Riebe will never see the outside of a prison again.

Watch Now:

Read more: The Sun, The Sun (2), Metro, Daily Mail, NWF Daily News, Evening Standard,,, The News Herald, (2), The Mirror, NWF Daily News (2), “86 Cold Case Could Be Warming Up: Suspect In Death Of Illinois Native Linked To 2 Other Killings,” Tribute Business News, Oct. 21, 2007

Next Up

6 Things To Know About Aileen Wuornos

Wuornos, a former sex worker, claimed that her victims had either raped or attempted to rape her, and her serial killings were committed in self-defense.

Prolific Serial Killer Nurse Charles Cullen May Have Killed As Many As 400 Patients

The murderer’s 16-year medical career in New Jersey and Pennsylvania ended after he was arrested in 2003.

Jeffrey Dahmer's Murderer Explains Why He Killed The 'Milwaukee Cannibal'

Christopher Scarver, who is serving time for killing his boss during a robbery, insists that Jeffrey Dahmer did not feel any remorse for his crimes.

Suspected Texas Serial Killer Taunted Police, May Have Committed Multiple Unsolved Murders, Cops Say

Before his May 2023 arrest, police say Raul Meza Jr. “was ready and prepared to kill again, and he was looking forward to it.”

The Internet's First Serial Killer: John Edward Robinson, The 'Internet Slavemaster'

John Edward Robinson was sentenced to death for his reign of terror in Kansas City in the mid-'80s.

'Golden State Killer' Joseph James DeAngelo Pleads Guilty To 13 Murders

“I destroyed all their lives. So now I’ve got to pay the price,” he reportedly has said.

UPDATE: Suspected Stockton Serial Killer Arrested

Since April 2021, six men were fatally shot and one woman was shot and wounded in central California.

Man Who Searched ‘How To Be A Serial Killer’ Charged In Murder Of Missing Texas Woman

24-year-old Felicia Johnson was last seen getting into an Uber on April 16, 2022 after leaving a Houston club. In February 2023, her remains were found but her killer remains at large.

Key Players in the Jeffrey Dahmer Case: Where Are They Now?

From 1978 to 1991, Jeffrey Dahmer raped, killed, and dismembered 17 boys and men.

How Elusive Serial Killer Ted Kaczynski Was Unmasked As The Unabomber

The self-professed anarchist was captured in 1996 hiding out in a primitive Montana cabin.