A 47-year-old Denver man suspected of killing three people at a Thornton Walmart had been haunted by voices telling him the devil was after him since a bad LSD trip damaged his brain 29 years ago, his stepsister says.

Michelle Willoughby, 43, said she’s unhappy with how stepbrother Scott Allen Ostrem has been portrayed on social media.

“My brother is not this monster,” said Willoughby, who lives in Cocoa Beach, Fla. “He is not cold blooded. He hears these voices. Honestly, in my heart, I believe there is only so much a person can take.

“I never thought something like this would happen.”

According to police, Ostrem casually entered the Walmart at 9901 Grant St. on Nov.1 at at 6:10 p.m., pulled out a handgun and began shooting. He allegedly fatally shot Pamela Marques, 52; Carlos Moreno, 66; and Victor Vasquez, 26. Thornton police arrested Ostrem Thursday morning.

Joe Amon, The Denver Post The Fobb family Angelique 13, Jason Fobb, Destiney 9, Marlena Fobb. Marlena Fobb is hugged by her daughter Destiney 9, as she tells her story of being in the check-out line with her husband Jason next to a man that was shot and killed in the shooting at Walmart in Thornton. "He saved my life, she said, talking of her husband, If he hadn't of threw me to the ground we were gone."

John Leyba, The Denver Post Rochelle Ginsner holds her daughter Danielle Carey, 16, an employee, after they were released from the parking lot at Walmart after a shooting at the store on Nov. 1, 2017.

Helen H. Richardson, The Denver Post Walmart employees and customers head away from the scene outside of the Walmart store where a shooting occurred inside the store at 9901 Grant Street on Nov. 1, 2017 in Thornton.



AAron Ontiveroz, The Denver Post Darlene Jackson sits on an overturned shopping cart as she and fellow shoppers and employees gather outside after a gunman opened fire near the Halloween section of Walmart at 99th and Grant Street in Thornton on Nov. 1, 2017.

AAron Ontiveroz, The Denver Post Employees Jose Delgado and Alexandra Adams stand outside after a gunman opened fire near the Halloween section of Walmart at 99th and Grant Street in Thornton on Nov. 1, 2017.

Joe Amon, The Denver Post Police at shooting in Walmart on Nov. 1, 2017 in Thornton.



RJ Sangosti, The Denver Post Witnesses walk from a bus to Thornton Civic Center after two men were killed during a shooting inside the Walmart Super Center iNovember 1, 2017 in Thornton.

John Leyba, The Denver Post Family and friends wait on a hill to hear word from their loved ones as emergency crews and police patrol the grounds of the Walmart after a shooting at the store on Nov. 1, 2017

Helen H. Richardson, The Denver Post A father and son, who were customers inside Walmart, are escorted out of the parking lot and away from the scene of the Walmart store where a shooting occurred inside the store at 9901 Grant Street on Nov. 1, 2017 in Thornton.



Helen H. Richardson, The Denver Post Employees gather together outside away from the scene outside of the Walmart store where a shooting occurred inside the store at 9901 Grant Street on November 1, 2017 in Thornton, Colorado. Two people were killed and one taken to the hospital after a shooting that started just around 6:00pm.

Helen H. Richardson, The Denver Post Police officers help a disabled man leave the parking lot outside of the Walmart store where a shooting occurred at 9901 Grant Street on Nov. 1, 2017 in Thornton.

AAron Ontiveroz, The Denver Post A Thornton police officer gives instructions to people as they stand outside after a gunman opened fire near the Halloween section of Walmart at 99th and Grant Street in Thornton on Nov. 1, 2017.



Helen H. Richardson, The Denver Post Walmart employees and customers that were inside the store wait to hear what to do from police as they stand behind police tape outside of the Walmart store where a shooting occurred Nov. 1, 2017 in Thornton.

Helen H. Richardson, The Denver Post Walmart employees and customers head away from the scene outside of the Walmart store where a shooting occurred on Nov. 1, 2017 in Thornton.

AAron Ontiveroz, The Denver Post A Thornton police officer watches as people are instructed to leave the parking lot after a gunman opened fire near the Halloween section of Walmart at 99th and Grant Street in Thornton.



AAron Ontiveroz, The Denver Post People stand outside after a gunman opened fire near the Halloween section of Walmart at 99th and Grant Street in Thornton on Nov. 1, 2017.

AAron Ontiveroz, The Denver Post Employees exit the parking lot after a gunman opened fire near the Halloween section of Walmart at 99th and Grant Street in Thornton on Nov. 1, 2017.

AAron Ontiveroz, The Denver Post People stand outside after a gunman opened fire near the Halloween section of Walmart at 99th and Grant Street in Thornton on Nov. 1, 2017.



John Leyba, The Denver Post Employees and shoppers are released from a holding area in the Walmart lot. Emergency crews and police on the grounds of the Walmart in Thornton on Nov. 1, 2017 during a shooting.

AAron Ontiveroz, The Denver Post A man in a Rascal is helped out of the parking lot as shoppers and employees gather outside after a gunman opened fire near the Halloween section of Walmart at 99th and Grant Street in Thornton.

Andy Cross, The Denver Post Bystanders on a hill at 98th and Grant across the street from a shooting investigation at a Walmart in Thornton on Nov. 1, 2017.



Andy Cross, The Denver Post Police investigate the scene of a fatal shooting at the Walmart in Thornton on Nov. 1, 2017.

AAron Ontiveroz, The Denver Post People are escorted out after a gunman opened fire near the Halloween section of Walmart at 99th and Grant Street in Thornton on Nov. 1, 2017.

Helen H. Richardson, The Denver Post Onlookers watch police activity at the scene of a shooting inside the Walmart at 9901 Grant Street on Nov. 1, 2017 in Thornton.



Joe Amon, The Denver Post Police investigate the scene of a fatal shooting at the Walmart in Thornton on Nov. 1, 2017.

Joe Amon, The Denver Post Police investigate the scene of a fatal shooting at the Walmart in Thornton on Nov. 1, 2017.

Joe Amon, The Denver Post Police investigate the scene of a fatal shooting at the Walmart in Thornton on Nov. 1, 2017.



Joe Amon, The Denver Post Police investigate the scene of a fatal shooting at the Walmart Super Center in Thornton on Nov. 1, 2017.

Helen H. Richardson, The Denver Post A young girl walks through the parking lot away from the scene outside of the Walmart store where a shooting occurred on Nov. 1, 2017 in Thornton.

Helen H. Richardson, The Denver Post A father and his scared daughter, who were customers inside Walmart, are escorted out of the parking lot and away from the scene of the Walmart store where a shooting occurred on Nov. 1, 2017 in Thornton.



Helen H. Richardson, The Denver Post THORNTON, CO - OCTOBER 1 - A father and his scared daughter, who were customers inside Walmart, are escorted out of the parking lot and away from the scene of the Walmart store where a shooting occurred on November 1, 2017 in Thornton, Colorado. Two people were killed and one taken to the hospital after a shooting that started just around 6:00pm.

John Leyba, The Denver Post Adams County Sheriff on the grounds of the Walmart in Thornton on Nov. 1, 2017 talking to witnesses after a shooting inside the store.

John Leyba, The Denver Post People are taken away from the Walmart on a bus on Nov. 1, 2017 in Thornton after a shooting inside the store.



Helen H. Richardson, The Denver Post Police guard the front entrance to Walmart where a shooting occurred inside the store at 9901 Grant Street on Nov. 1, 2017 in Thornton.

Willoughby called The Denver Post from a boat in the “middle of the (Atlantic) Ocean” after receiving death threats and hate emails after she tried to defend her brother on social media.

Willoughby believes she can trace what led to the fatal shooting to a drug party her brother attended in 1988, where he ingested 16 doses of the powerful hallucinogen LSD. His life and the lives of his family members were forever changed, she said. But Ostrem only received counseling from his priest and never saw a mental health professional, she said.

Willoughby says she is heartbroken for the three victims and the other people who were in the store. She knows that they will forever be affected, but she believes her brother was not in his right mind.

“I love my brother. I stand behind him. I’m not going to stop loving him. I love him unconditionally,” she said.

Before taking LSD, Ostrem was an outgoing, social person who sometimes had multiple girlfriends. He played football, water skied, fished, hunted and went camping every weekend in the summer. He spent hours in the gym.

“My brother was a people person. He had a different aura,” Willoughby said. “I adored him.”



But Ostrem’s effervescent personality changed immediately after the party, she said.

“When he came home he was terrified. He had voices in his head. Demons. My brother was freaking out,” she said. “He was screaming that the devil was after him.”

The family contacted a hospital for help, but Ostrem received only drug intervention.

Family members, who were Catholic, mostly attended mass at Christmas and Easter.

After the bad drug trip, a priest began visiting with Ostrem three times a week. His interest in Ostrem lasted for years.

The priest would read the Bible with Ostrem and spent hours during each visit. Although the family left the pair so they’d have their privacy, Willoughby said on dozens of occasions she saw the priest place a crucifix on Ostrem’s forehead and bless him. The priest commanded demons to leave his body and asked God to halt the voices in Ostrem’s head.

“He cared about my brother,” said Willoughby. “It wasn’t like we went to church. The church came to us.”

Willoughby couldn’t remember the priest’s name, but said after he died, Ostrem continued to read scriptures.

But the voices returned and Ostrem became a recluse, his sister said. Those voices told him that his neighbors, people he met on the street and people driving cars next to him in traffic were demons, Willoughby said.

Following the shooting several of his former neighbors said Ostrem was hostile. Some friends and family told him to snap out of it, that he was just seeing and hearing things that didn’t exist.

Willoughby remained one of the few people Ostrem would speak with. Eventually he even stopped speaking with his own father, she said.

“My job as his sister is to help him any way I can,” she said.

When Ostrem told her that he knew she was 150 years old, Willoughby went along, telling her brother that because since she was his older sister it was his responsibility to listen to her advice, including attending school and sporting events of his nephew and niece.

But shortly after his grandmother died, Ostrem quit his job and moved into the mountains. He lived alone and bow hunted and fished.

“He went off the grid. Nobody could find him. Not one person on the face of the Earth knew where he was,” Willoughby said.

She didn’t hear from Ostrem for three years and fears he was “alone with himself way too long.”

She told family members that they needed to have Ostrem committed to a hospital for a mental evaluation, but that wasn’t ever done and he was never diagnosed with a mental illness.

Last week, Ostrem walked away from his job as a metal fabricator without telling his boss what he was doing or whether he would return. He didn’t.

Willoughby said she doesn’t know what triggered her brother’s rampage because she hasn’t been able to speak with him.

But she believes something that would seem trivial to most people was twisted into something large in her brother’s mind.

When she saw pictures of her brother following his arrest in the Walmart shooting, Willoughby was shocked by his appearance.

Provided by Thornton Police Department Scott Ostrem in 2017

Provided by Wheat Ridge Police Department Scott Ostrem in 2014

Provided by Wheat Ridge Police Department Scott Ostrem in 2013



“He lost so much weight,” she said. “When my brother spoke I couldn’t recognize his voice. I can’t imagine what is going on in his mind right now.”

But her brother may finally get the psychological help he desperately needs, she said.

“He’s at the worst possible starting point.”