Credit: Delaware County District Attorney Office
District Attorney Jack Stollsteimer and Captain James B. Kemm of the Pennsylvania State Police announced charges against Wayne Anthony Walker, 58, in connection with the murder of Denise Marie Pierson, an 18 year-old Marcus Hook resident who disappeared on the night of April 14, 1981. The victim’s remains were discovered in July 1984. An autopsy conducted in 1984 determined that the victim died as a result of blunt impact injuries to the head, and the manner of death was homicide. Following an extensive joint re-examination of the nearly 40-year-old evidence and case facts, Walker has been charged with criminal homicide, murder of the first, second, and third degrees, kidnapping, and conspiracy.
Peter Horne, formerly a Marcus Hook resident, is identified as a co-conspirator in the murder of Denise Pierson, but is deceased and cannot be charged. Two additional suspects are under investigation in connection with this case. There is a $5,000 reward for information that leads to the arrest of additional suspects.
The homicide was originally investigated by the Pennsylvania State Police. The cold case was re- opened by the Criminal Investigation Assessment Unit of the Pennsylvania State Police in 2018, and the Delaware County District Attorney Office joined the investigation. In re-opening the case, the Pennsylvania State Police reviewed all of the evidence in the case, and implemented various new investigative tools and strategies to further the investigation. In the course of their review, investigators learned of the existence of a 6 inch folding knife that had been recovered with the victim’s remains, and stored by the Delaware County Coroner’s Office. This discovery led to a further examination of the evidence gathered regarding the victim’s remains, which provided information crucial to the charges brought today.
On April 14, 1981, Denise Pierson failed to return home from a visit to a friend’s house in Marcus Hook. In January 1984, the Crisis Intervention Center at Crozer-Chester Hospital received a call from an unidentified caller who stated that he had killed Denise Pierson. The call was traced to the home of Peter Horne in Marcus Hook. A search warrant was executed at the Horne residence, and two black jacks (a leather Billy club) were recovered. Horne denied making the calls to the crisis center. In February 1984, investigators interviewed the owner of a garage that employed Horne, who confirmed that the victim’s mother had her car serviced at the garage. The victim’s mother confirmed that the victim had been with her on several occasions at the garage. Investigators determined that Horne left his employment with the garage the day after the victim’s disappearance.
On July 18, 1984, the skeletal remains of the victim were found in the vicinity of the railroad tracks located at 7th and Market Streets in Marcus Hook. The site was approximately 300 yards from the Horne residence. An autopsy conducted in 1984 determined that the victim died as a result of blunt impact injuries to the head, and that her manner of death was homicide.
In March 1994, investigators conducted an interview of “Suspect 1.” Suspect 1 stated that the victim had come to his apartment on the day of her disappearance. He stated that the victim was “naïve” and “trusting.” He stated that he believed that defendant Walker and “Suspect 2” were capable of the murder.
In June 1994 investigators conducted a search of the residence previously occupied by Horne. Items seized from the crawl space included segments of rope and multiple pieces of cardboard boxes.
In August 1994, Investigators received information from a former cellmate of defendant Walker. Defendant Walker had admitted to his cellmate he had been at a party at Peter Horne’s residence with the victim and others, including Suspect 1. According to the cellmate, Walker stated that at one point Horne and the victim left the party to go to Delaware. When they returned to the residence, the victim was upset and placed a call to her mother. Suspect 1 grabbed the phone and Horne hit her in the head with a black stick. Horne, Suspect 1, and Defendant Walker carried the victim to the train tracks. Defendant Walker admitted to assisting Suspect 1 and Peter Horne in burying the victim.
Throughout 1994 – 1995, investigators interviewed defendant Walker on numerous occasions. Defendant Walker stated he was present at Peter Horne’s house when Horne, Suspect 1, and Suspect 2 killed the victim. Walker told investigators that on the day of the incident, they played a game called “spin the stick”. During the game, the victim charged for the door in an attempt to flee the residence. Defendant Walker stated that Horne then hit the victim with a stick and she started to bleed. Suspect 2 provided Horne with clothesline which he used to tie up the victim. Horne then placed the victim in green trash bags. Horne, Suspect 1, and Suspect 2 carried the victim to a wheelbarrow on the patio. Defendant Walker stated they all took the victim to the “Tracks,” which were located behind the Marcus Hook school parking lot. At the parking lot, they removed the trash bags. Defendant Walker stated Suspect 2 hit the victim with a railroad spike. Defendant Walker stated the victim was not buried – they just covered the body with bushes. Defendant Walker stated he had been threatened by Horne and Suspect 1 to remain silent about the murder. Walker stated that he had returned to the site where the victim had been dumped to have sex with the corpse.
In December 1994, based on information provided by defendant Walker, investigators conducted a search around the concrete storm sewer junction box in Marcus Hook. Investigators recovered rope, clothing, debris and a piece of jewelry. Investigators conducted a forensic analysis of the rope recovered from the storm sewer junction box and the rope recovered from the Horne residence. It was determined that the twine within the rope was similar..
In June 1995, investigators spoke with the wife of Horne. She confirmed that he kept a wheelbarrow at the house, as well poles with several clotheslines. She also stated that Horne kept a weapon hidden in the basement of the residence. A search warrant was executed and a .32 caliber derringer style handgun was recovered, as well as a Billy club. Peter Horne was subsequently arrested for firearms violations.
Peter Horne was again arrested in 1997 on charges of stalking. Horne was sentenced to a minimum of six years and six months to nineteen years incarceration at State Correctional Institution – Mercer. Horne died while incarcerated in 2013.
Investigators re-interviewed Horne’s wife in March 2013. During the interview, she admitted that she had been told to lie by Horne when investigators asked about the blackjacks that had been found at the residence. She stated that she believed that Horne had killed the victim.
In 2018, investigators began to conduct numerous interviews of current and past acquaintances and family members of all involved suspects. Investigators learned that as time had passed, the suspects had begun to discuss details of the murder of Pierson with numerous acquaintances. Investigators began to compile and corroborate these details with case facts and evidence
In July 2021 Trooper First Class Andrew Martin engaged the services of Forensic Anthropologist Erin Kimmerle, Florida Institute of Forensic Anthropology and Applied Sciences at the University of South Florida. Kimmerle conducted an overall review of the Medical Examiner’s report, notes, and photographs regarding the remains of the victim. She also reviewed the case evidence amassed by the Pennsylvania State Police. In October 2021, Kimmerle issued a report based on her re-examination of the evidence and found that the victim sustained a sharp incised cut along the right mandibular notch, which is the area in the skull above the jaw and adjacent to the ear. She further stated that the puncture wound was an injury resulting from a sharp edged object, and that the cut occurred at the same time as other injuries. Kimmerle opined that the blunt and sharp injuries observed and described were consistent with having been inflicted by the recovered 6 inch folding knife as well as the recovered “black jacks” from Peter Horne’s residence. Kimmerle’s discovery of the knife wound aided investigators in corroborating witness and suspect statements.
“As with any cold case Homicide Investigation, the passage of time should not be looked at as a burden to the investigation, but rather an advantage. It is often found that relationships change throughout the years. Witnesses who may have been reluctant to come forward in the past, are now more willing to assist. People previously confided in by suspects because they were trustworthy may not have the same loyalty’s 40 years later, and this is exactly what we have found with this investigation” said Trooper First Class Martin.
“Sadly, this case has an extremely long and complicated history. As the chronology demonstrates, over the decades, investigators continued to work the case, but were unable to reach the threshold that would permit them to bring charges. Today, with the assistance of an expert in forensic anthropology, we are finally able to provide the victim’s family with answers about what happened to their loved one. In addition to applauding the work of the Pennsylvania State Police on this investigation, I want to acknowledge the hard work and dedication of Assistant District Attorney Geoff Paine, who leads our office’s review of cold cases. These cases can feel hopeless, but as today’s charges make clear, with the new tools and technology that emerge every day in the field of forensics, we must never give up,” said Stollsteimer.
Anyone with information should contact Trooper First Class Andrew J. Martin, Criminal Investigation Assessment Unit, Pennsylvania State Police, Troop K, Philadelphia, at 215-452-5216.
Republished courtesy of Delaware County District Attorney’s Office.