Trial begins in killing of SLO woman whose body was dumped in Prefumo Canyon creek

The trial of the man accused of killing Kristen Marti four years ago and dumping her body in a San Luis Obispo creek got underway Wednesday with opening statements and the first witness testimony.

Robert Koehler, 40, of Arroyo Grande is accused of slashing Marti’s throat and weighing her body down with rocks in a flowing Prefumo Canyon creek in January 2018. He is charged with one count of murder with a sentencing enhancement for using a deadly weapon — a knife. Koehler entered a not guilty plea to the crime in June 2018.

Marti was last seen alive in a parked vehicle in the Prefumo Canyon area on Jan. 9, 2018, and her body was found in a Prefumo Canyon creekbed in March 2018 following a large-scale search.

San Luis Obispo police Officer Greg Benson testified in a 2018 preliminary hearing that Marti and her boyfriend, Nicholas Reed, were habitual heroin and methamphetamine users. Benson said he had heard rumors Marti supported their habits through sex work.

Koehler has remained in San Luis Obispo County Jail custody without bail since he was arrested in May 2018.

Judge Jesse J. Marino is overseeing the case, and a jury will decide the verdict.

Koehler fantasized about ‘killing whores’ in writings, prosecution says

Deputy District Attorney Lisa Muscari opened the trial by providing a detailed timeline of the events that occurred on Jan. 9, 2018, the last day Marti was seen alive. She said Marti lived “a broken life” as a sex worker and drug addict living on the streets of San Luis Obispo.

“She had no idea who the defendant was,” Muscari said. “She had no idea what the defendant was capable of. She had no idea that he was going to be her end.”

Muscari said Koehler had contacted Marti multiple times before their Jan. 9 meeting, using a phone number on a third-party messaging app, TextPlus, which concealed Koehler’s real phone number. He asked her to meet and offered her cocaine and “a donation,” meaning money traded for a sexual experience, Muscari said.

Muscari said Koehler was frustrated over a sexual relationship with an employee he had hired to be both his assistant and sex partner. Muscari said Koehler “could not get it up,” and so later that day — Jan. 9, 2018 — he contacted Marti.

Jan. 9 also happened to be Koehler and his wife’s wedding anniversary.

In a search of Koehler’s house, police found a bag that contained gruesome and threatening writings in which Koehler fantasized about “killing whores,” Muscari said. When asked about them, Koehler allegedly said that they were “his raps,” she added. Additionally, Muscari said that inside the bag, police also found that Koehler had a list of “20 ways to not get nabbed.”

Marti’s body was found to contain traces of Telozol — an anesthetic used on cats and dogs — along with significant amounts of alcohol, cocaine, morphine and methamphetamine. Koehler’s browser history also revealed that he had searched for ways to acquire the Telazol and another animal tranquilizer, Muscari said.

Muscari said that Telozol is rarely found in people. She said that according to a toxicology database, out of 360,000 people that had been tested for Telozol between 2019 and 2021, only one person had tested positive.

The night of Jan. 9, Muscari said that Koehler’s wife attempted to contact him multiple times. His phone pinged a cell tower near Prefumo Canyon around 7 p.m. before he stopped having cellular signal for around two and a half hours, when his phone pinged a cell tower near Avila Valley Drive and Highway 101.

When Koehler was questioned as to why he didn’t have a cell signal, he’d said he was stuck on the side of Los Osos Valley Road, a statement that was refuted by a police officer on duty in the area, Muscari said.

Although Koehler didn’t have cellular signal at that time, Muscari said that Koehler’s iPhone still recorded his movements through the Health app, revealing he was walking and gaining elevation during the time his GPS was not traceable on his phone.

Muscari claimed that Koehler immobilized Marti and then slit her throat. She concluded her opening statement saying that on the night of Jan. 9, “Kristen Marti stepped into a nightmare.”

Defense tells prosecution to ‘bring it on’

Defense attorney Trace Milan began his opening statement by asking a rhetorical question: “Do you know what’s true beyond a reasonable doubt or just what might be true according to drug addicts, homeless people, drug dealers and boyfriends who line up dates (to perform oral sex) for money?”

He said the evidence does not show that Koehler killed Marti, but rather that men who cheat on their wives on their anniversary do not answer their wives’ calls or texts while in the act and turn off their location services to avoid being caught.

Koehler was arrested in Minnesota in May 2018 and held in Hennepin County jail before being transferred to San Luis Obispo County.

Milan claimed that Koehler and his wife did not “flee” San Luis Obispo County pending the investigation into Marti’s death, but rather moved to Minnesota because their landlord threatened to kick him out after multiple police search warrants.

When it came to the Health app, Milan said the number of steps and elevation gain does not match the terrain where Marti was found.

Milan did not address the writings or animal tranquilizers in his opening statement.

“Bring it on,” Milan told the prosecution at the close of his statement.

First witness testimony begins

Nickolas Reed, Marti’s boyfriend at the time, was the first witness called to the stand by Muscari.

Reed said he met Marti in 2012 and the two became boyfriend and girlfriend. They routinely drank alcohol and did heroin and methamphetamine throughout the entirety of their relationship, Reed said, but he has now been sober for a year and a half.

Reed said Marti was kind, loving and down to earth, adding she told him drugs and alcohol made life tolerable for her.

“I feel like she tried to numb herself from the world,” he said.

To Reed’s knowledge, Marti did not buy cocaine because it was too expensive. She would only do cocaine if it was given to her for free, he said.

He did not describe their relationship as an “open relationship” but was aware that Marti would go on dates for a “donation.” He said she would only seek out sex work if they ran out of drugs and money. They usually relied on Reed’s Social Security income of around $850 a month to survive, he said.

“She did what she wanted to do, and I couldn’t force her to stop what she was doing,” he said.

Reed said he had spent the day with Marti on Jan. 9, 2018, before she went on her date with Koehler. They were unhoused at the time, living in a field near Marsh and Higuera streets. He said they were always together except for maybe a few hours per day, so the fact that she was gone all night was unusual.

He does not recall Marti drinking alcohol that day. The day began with a morning dose of heroin, then they ate breakfast and met up with a friend who drove them to buy drugs.

Reed said he saw Marti setting up a date while he looked over her shoulder as they were driving — he was in the back seat and she was sitting in the passenger seat.

The friend drove to the Conserv station across the street from Santa Rosa Park, where Marti “jumped” out of the car and disappeared. Reed testified that he did not see where she went and she did not say where she was going. He said Marti would be angry if he tried to follow her.

The friend injected heroin in the bathroom and they waited at the station until they decided to leave to find more drugs, he said. Reed said he was calling and texting Marti the whole time, but only received one message from her saying she was on Prefumo Canyon Road. He said he and his friend drove to the road and saw Marti with an individual inside a red car, but as they got closer a voice from the car told them to go away.

Reed continued to call and text her the following day, and also called the police station a few days after she went missing. The station told him to check her usual spots and ask around, which he did.

About a week later, San Luis Obispo police Officer Greg Benson stopped Reed for having an open container of alcohol, and at that time, Reed asked Benson if he had seen Marti. Benson said he had not and would ask other officers if they had seen her.

Reed testified that he filed a missing persons report with the San Luis Obispo Police Department a few days later and gave the department his phone to search.

Reed confirmed that a photo of a methamphetamine pipe was shown to him by San Luis Obispo police Det. Caleb Kent. He said the pipe looked like Marti’s because it had burn lines that were specific to smoking the “stem” of meth, which they would do if they were low on drugs. He said Marti always kept the pipe in her purse.

He said he yelled at Kent after he saw news reports of Marti’s body being found because he was upset that Kent did not tell him about her body earlier.

“I was out of sorts,” he said.

Milan began his cross examination by asking if Reed knew what Marti looked like while it was dark outside, which Reed said he did.

Reed testified that he struck Marti one time throughout their relationship and that Marti struck him multiple times, but he would not describe himself as a “battered man.”

When asked about a previous domestic violence charge where Reed was accused of hitting his partner, choking her and pulling her out of a car by her hair, Reed said the woman called the district attorney six months later saying she lied and got the charge plead down to misdemeanor domestic assault.

The Tribune was unable to immediately confirm these details with court documents because the detail came after the court computer closed.

The court adjourned before Milan finished cross-examining Reed, but is set to resume Thursday at 10 a.m.

This story was originally published June 1, 2022 at 7:36 PM.

Chloe Jones

The Tribune

Chloe Jones is a former journalist for The Tribune

Mariana Duran

The Tribune

Mariana Duran is a reporting intern at the San Luis Obispo Tribune. She is a media studies and cognitive science double major at Pomona College.