How did the police solve Trina Langenbrunner's murder case after 12 years?

Police used witness testimonies to solve Trina Langenbrunner's September 2000 death and arrested 41-year-old Joseph Couture of Cloquet years later in 2012. Langenbrunner, a mother of three, was found brutally stabbed to death in a gravel pit near the Fond du Lac Reservation in Minnesota. The case remained unsolved until witnesses came forward, revealing key evidence.

In 2013, Couture finally pleaded guilty to intentional second-degree murder, first-degree aiding and abetting aggravated witness tampering, and aiding and abetting first-degree arson. He was sentenced to 40 years as part of a plea deal. His girlfriend, Sandra Couture, who assisted him in covering up the crime, also pleaded guilty and was given a nine-and-a-half-year prison term.

ID's Murder in the Heartland chronicles Trina Langenbrunner's decades-old case in an episode titled Killer on the Res. The synopsis of the episode reads:

"When someone stabs Trina Langenbrunner to death and leaves her on a road in Cloquet, Minn., her family, community, and law enforcement work together for over 12 years to find her killer."

Killer on the Res will air this Wednesday, March 15, 2023, at 9 pm ET.

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Anonymous witnesses testified against Joseph Couture, who was arrested in Trina Langenbrunner after 12 years

Joseph Couture pleaded guilty in connection to Tina Langenbrunner's murder 13 years later (Image via Minnesota Department of Corrections)

According to reports, an anonymous witness informed authorities that Joseph Couture, 41, of Cloquet, went to the Brookston Bar, also known as Stoneybrook Saloon, on the night of September 2, 2000. The witness was only awakened when Couture returned home and saw him covered in blood. Couture then lit a fire, removed his clothes, and burned them, including his New Balance shoes.

The witness later mentioned that Couture drove his ATV towards the river behind the house. When he returned, he instructed that his vehicle be cleaned right away before he went to take a shower. The van's exterior and steering wheel were reportedly covered in massive amounts of blood.

The witness claimed that Couture commented about his efficiency in killing someone later that day due to having previously done so. As per the witness's account, he threatened to kill them in a similar manner in which he murdered Tina Langenbrunner.

Before September 3, the witness alleged that they had seen Couture carrying a knife sheathed on his belt. That was the last time they ever saw that knife. They said Couture claimed that he threw away evidence on the route.

At the location where Trina Langenbrunner's body was discovered on the morning of September 3, investigators discovered tire tracks and shoe patterns for both Couture and Langenbrunner. It was determined that a Dodge or Plymouth minivan made the tire marks and that the suspect's New Balance shoes had a similar pattern to the one found at the crime scene.

At the time, Couture owned an older model gray Dodge minivan, and a witness reported seeing a similar car sometime around 3 am near the crime scene.

One of them even revealed that the accused confessed to committing the crime. They claimed that Couture expected to have s*x with Langenbrunner that night, but she allegedly rejected him. The witness further stated that Couture told them he "snapped," after which "it went brutal." He then "whooped the dog s**t out" of her, "stabbed her," and "choked her out."

In 2013, Joseph Couture finally pleaded guilty and confessed to stabbing 33-year-old Trina Langenbrunner on September 3, 2000. The victim died of blood loss from at least 29 stab wounds on her torso, face, and back. Couture also claimed that he and his girlfriend, Sandra Couture, had planned a strategy to intimidate witnesses and persuade them not to testify against him.

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Murder in the Heartland will discuss Trina Langenbrunner's in detail this Wednesday on ID.