'My instincts kicked in': Man stabbed neighbor 11 times during fight over motorcycle parking while victim's mother begged him to stop

Left: Chad Westover (Clackamas County Sheriff's Office). Right: Tristan Thomas (GoFundMe). Inset: The knife Westover used to kill Thomas (Clackamas County Sheriff's Office).

An Oregon man is headed to prison for stabbing an off-duty U.S. Postal Service mail carrier to death during an altercation at their apartment complex, later telling a judge his "instincts kicked in."

Chad Michael Westover, 53, was sentenced to 25 years behind bars for the slaying of 43-year-old Tristan Salvatore Thomas. He was convicted last year of second-degree murder and unlawful use of a weapon, according to the Clackamas County District Attorney's Office.

Thomas' mother Beth Kostelnik urged the judge to impose the strongest possible sentence.

"He has shown no remorse for killing my son and taking him away from us," she told the judge, local Fox affiliate KPTV reported. "He has just shown arrogance through this whole court system. I think if he gets out he is going to do it again."

Westover apologized for killing Thomas while also trying to explain his actions.

"My instincts kicked in. I'm sorry," he reportedly said. "I think forgiveness is the best revenge. We will get there over time, I hope."

While Westover had a limited criminal history, prosecutors noted he was kicked out of a grocery store about a month before the murder, according to The Oregonian. He reportedly had a gun in his vehicle and told responding officers he was "prepared to die." Westover also lost his teacher's license in the early 2000s for using force while disciplining students, the outlet reported.

Kostelnik called her son's killer "a walking time bomb."

Westover and Thomas were scuffling on Sept. 21, 2024, when the now-convicted murderer told pals to stop filming the ordeal so he could "handle it." He attacked Thomas with a kitchen knife as the victim's mother looked on. Thomas died at a hospital on Oct. 3, 2024.

"Several neighbors and Thomas' mother yelled at Westover, who was on top of Thomas and stabbing him with the kitchen knife, to halt the assault. Westover was also injured during the altercation. Thomas was stabbed several times and suffered a 4-inch slash to his left vertebral artery," the DA's office said.

The suspect fled the scene but was arrested a few days after the attack. His lawyers claimed Thomas was the aggressor and was an "unreasonable and unstable man" who was drunk the night of the crime, prosecutors said.

As Law&Crime previously reported, the incident happened at the Twin Creek Apartment complex on SE Sunnyside Road in Clackamas, just outside Portland, the Clackamas County Sheriff's Office said at the time.

According to a 168-page probable cause arrest affidavit obtained by Law&Crime, the ordeal actually began earlier in the day when Thomas confronted a neighbor, Christopher Stewart, over the way he parked his motorcycle at the apartment complex where they both lived. Stewart allegedly assaulted Thomas, sending him to the hospital. Deputies did not believe there was enough probable cause for an arrest, the affidavit stated.

After receiving treatment, Thomas returned from the hospital later in the day. Meanwhile, Stewart and Westover were at a party in the complex hosted by 48-year-old Samantha S. Christensen. At some point, Stewart received a call from his teenage daughter claiming that she was being followed by a "strange man" in the complex, the affidavit said. Stewart, Westover and Christensen left the party to investigate. They reportedly determined the man was Thomas, who was allegedly carrying a butcher knife.

Much of what occurred next was captured by neighbors taking video of the altercation and from Thomas' calls to 911, authorities said. Deputies did not release footage, but the affidavit included stills.

In the call, Thomas told dispatchers that four people later identified as Stewart, the teen daughter, Westover and Christensen were outside his apartment and he feared for his safety. A video taken by a neighbor allegedly shows Westover say, "If you guys are done filming, I'll take care of it," to which Christensen, who is the defendant's cousin, replies, "I'm done, take care of it, Chad."

Westover goes off screen and apparently attacked Thomas, the affidavit said. During the altercation, Thomas "repeatedly screams for help" as Westover assaulted him, deputies wrote. Stewart yells at Westover to "let him go, let him go" as Thomas exclaims "He's stabbing me!," the affidavit said.

The neighbor taking the video urges someone to call 911 because "that's a lot of blood!" per the affidavit. Westover's assault lasted nearly 5 minutes, authorities said. He allegedly then threw the knife atop Thomas and walked away. Deputies say Thomas never caused harm to Westover.

"After leaving Mr. Thomas in a pool of his blood, Defendant left the scene with Samantha Christensen and at no point called 911," detectives wrote. "In fact, I know that Samantha Christensen took Mr. Thomas's phone from the scene, and when 911 called back from the dropped call, she told them that everything was 'fine' prior to hanging up the call."

Christensen turned herself in to the Clackamas County Jail on charges of first-degree assault, tampering with physical evidence, hindering prosecution and interference with making a report.

After receiving her Miranda warnings, Christensen told detectives it was Thomas who first attacked Westover with the butcher knife and sliced him under the eye and stabbed him under the rib cage. She took photos of his injuries. Investigators called the placement of the wound "curious" and noted he had no defensive wounds. Deputies also said when Westover went to the hospital for treatment, he claimed he had been in a motorcycle accident.

Thomas' family started a GoFundMe to cover funeral expenses and other costs.

"Tristan was a pillar to his community giving back by delivering mail to the same community he grew up in. He is described as quirky, boisterous, lovable, vibrant and had a presence about him that brought a smile to many, you always knew when he was in the room," the fundraiser said.