William Michael Dennis killed Doreen Erbert on Halloween in Berryessa, San Jose, California, on October 31, 1984. For the crime, Michael Dennis, also known as William Michael Dennis is on California’s death row. Next week, Unmasked will retell the story on Investigation Discovery. Doreen Erbert was eight-months-pregnant when she lost her life as her four-year-old daughter, Deanna, hid behind a sofa. The Doreen Erbert-William Michael Dennis Halloween murder loosely inspired the 2007 Lifetime movie, My Neighbor’s Keeper.
On Halloween night in 1984, San Jose detectives arrived at the home of Doreen Erbert. The victim’s husband, Charles Erbert, was outside covered in blood. He told detectives he found his pregnant wife dead on the floor. Investigators considered him a suspect because he refused to answer questions. He also smelled of alcohol.
By the time they reached the police station, Charles Erbert had calmed down. He begged investigators to believe that he had nothing to do with Doreen Erbert’s death. He told them that he left his home at 8:45 p.m. to buy more candy and later stopped at a neighbor’s home for a Halloween party. The Erberts’ daughter, Deanna Erbert Peterson (now Deanna Scott) had already gone trick or treating earlier that evening. During the police interrogation, Charles learned that his baby was also deceased.
To see if anyone had any information, the detectives canvassed the neighborhood and posted photos of the mask. Soon, a few people came forward with information. One person told investigators, he saw a man wearing mechanics overalls and a wolf mask between 8:30 p.m. and 8:45 p.m. The stranger was heading to Doreen Erbert’s house. Another person came forward and dropped a bombshell, revealing they had a photo of Doreen Erbert’s ex-husband, Michael Dennis (William Michael Dennis,) wearing the same mask at a Halloween party years earlier.
Sure enough, when detectives took a look at the photo, it matched the mask found at the crime scene. With that shocking information, investigators dove deep into William Michael Dennis’ background and discovered Doreen Rae Erbert married him in the 1970s. One child named Paul Dennis was born from that union. Detectives learned something else, something that could be a motive in the killing.
Paul Dennis drowned in Doreen Erbert’s swimming pool in 1980 when he was just three-years-old. Michael Dennis was distraught over his son’s death. He despised Doreen Erbert, who he believed wasn’t watching young Paul. And she hadn’t properly fixed the gate leading to the pool as promised. His concern stemmed from an earlier accident. The Erberts’ dog drowned in the same pool, according to court records.
In 1982, William Michael Dennis filed a wrongful death lawsuit against her. During that court hearing, he accused Doreen Erbert of cheating on him several times during their marriage. He also said she used substances (MJ) while taking care of their son, Paul. What disturbed Michael Dennis was his son never wanted to go to Charles and Doreen Erbert’s house. He said he believed they mistreated him. And the last time he had to transport Paul to see his mother, the boy begged to stay home. Paul drowned later that day. Though his story was tragic, the courts ruled against Michael Dennis.
For seasoned detectives, this new information meant he was at the top of the suspect’s list. When they first visited his home, Michael Dennis wouldn’t answer the door. They had to get him on the phone to tell him he must speak with them about Doreen Erbert. While talking to him, detectives noticed the bloody gauze Michael Dennis had wrapped around his fingers, which he said happened while playing with a blade.
A search of the home turned up bloody jeans, drops of blood on the kitchen floor, and more blood on the washing machine. But what detectives discovered in the garage was even more disturbing—two empty coffins. Police took him into custody. At the station, Michael Dennis said he didn’t kill Doreen Erbert. He also denied knowing anything about a mask. William Michael Dennis was charged with the death of Doreen Erbert and her unborn child.
William Michael Dennis’ Murder Trial
The former Lockheed Missiles and Space machine operator’s trial was held in July of 1988. William Michael Dennis’ friends and relatives testified about his troubled childhood. He had a problem with his hearing and stuttered when he talked. He was also overweight and had few girlfriends. Others spoke of William Michael Dennis’ bout with depression, which they say was brought on by Paul’s death and the recent loss of a good-paying job. Many who knew William Michael Dennis said he was a good father and that his son was everything to him. They later admitted he seemed obsessed with Doreen Erbert after losing Paul.
Investigators testified that Michael Dennis pretended to be sleeping when they arrived. His response was also suspicious. When they informed him of Doreen Erbert’s death, he simply said, “You’re kidding.”
In the end, William Michael Dennis revealed what really happened.
According to William Michael Dennis, he fantasized about getting rid of Charles and Doreen Erbert after Paul died. His plan was to kidnap them, put them in a wooden coffin, and drown them in the bay.
At 6:00 p.m., on Halloween night, William Michael Dennis ate dinner with his mother and took a piece of mail to a neighbor. The neighbor said she last saw him at 6:30 p.m. He told her he was going to a Halloween party. His mother left the house briefly but returned home and slept. Michael Dennis said he put on the mask, white gloves, and left his home on foot, taking the overpass to reach Doreen Erbert’s home.
When Doreen Erbert opened the door, little Deanna heard him say, “You killed my boy.” Then he told her, “I’m going to kill you.” Doreen Erbert said, “Get out of my house!” But after her ex-husband raised the eighteen-inch machete, she screamed out to Deanna, “Hide!”
Prosecutors say weeks earlier someone saw Doreen Erbert in the store and informed William Michael Dennis that she was pregnant. But Dennis said he didn’t know until the fetus dropped onto the floor. He said he never touched the baby. According to a report that was entered at trial, Dennis also said Doreen Erbert struggled as he asked her, “How does it feel to drown?” She spoke to him for about sixty seconds before blacking out.
Charles Erbert returned home and found Doreen Erbert lying on the floor in the front room. To his horror, the fetus was not inside her. It was on the floor next to her. At first, he thought she had gone into labor until he glimpsed a severed hand and a fetus leg next to her. It was a miracle Doreen Erbert was still breathing. But Charles Erbert couldn’t help her. He tried to run to the phone to call 911 but slipped and fell in the blood. Before he left to get help, he remembered his daughter was in the house. He found her hiding behind the couch and whisked her off to neighbor Jennie Chapman. Then, he accompanied detectives to the station.
William Michael Dennis was found guilty of killing Doreen Erbert in August of 1988. Upon hearing the verdict, he listened without showing emotion. When he was led out of the courtroom, he turned to Doreen Erbert’s family and said, “Good night.” Doreen’s relatives broke down in tears. At his sentencing hearing in September, he told her family that he was sorry. Though, he blamed Doreen and Charles Erbert for not making sure the fence was stable.
Before he passed away in 2007, Frank Hitchens, Doreen Erbert’s father, said his daughter’s murder ruined his entire life and that he’d kill Michael Dennis if he ever saw him outside of prison. Catherine Hitchens, Doreen Erbert’s mother said she’d gladly hire someone to kill him if he got out. A medical examiner’s report stated Doreen Erbert’s baby never lived outside the womb.
Charles Glenn Erbert filed a lawsuit against the city of San Jose for being arrested falsely in front of the neighbors. Unmasked: “The Big Bad Wolf” airs Monday at 10 p.m. on ID.
[Main image via Investigation Discovery/Permissions granted]