COLUMBIA COUNTY, Wis. (WFRV) - Following a week-long trial that ended with the jury deliberating for over 12 hours, the Wisconsin man accused of killing his girlfriend back in 2022 was found guilty. Court records show that 80-year-old Larry Manthe was found guilty by a jury on a charge of 1st-Degree Intentional Homicide on Friday, January 10. On October 6, 2022, family members of 76-year-old Alice Langer called authorities advising they had not been able to get in contact with her for over 15 hours. When deputies arrived at Langer’s residence, they found her dead inside the house with a gunshot wound to the head. Oshkosh Police Department rescues human trafficking victim, arrests suspect with extensive criminal history The investigation continued for months with detectives actively pursuing countless leads with no primary suspect in custody. However, a breakthrough in the homicide investigation finally came nearly a year after Langer was found dead. On September 15, 2023, Manthe was arrested for the death of Langer. Manthe and Langer had reportedly been living together and were in a long-term relationship at the time of Langer’s death. It was learned that Langer had intended to end the relationship and move out of the house. Suspect arrested, charged in connection to officer involved shooting in Wisconsin On Facebook, the Columbia County Sheriff's Office stated that the jury had deliberated for over 12 hours. The post also shared the Office's thoughts on the investigation: There are no winners when someone takes another person’s life as the entire community and both families suffer but we are grateful that the family of Alice Langer gets justice and some closure to this senseless act of violence...There was a lot of investigative work by our entire detective division led by investigators Brian Johnson and Tim Schultz. Their hard work and determination were what drove their efforts to find the truth. Columbia County Sheriff's Office Court records do not yet show when Manthe will be sentenced. Local 5 will provide an update to this story after Manthe receives his sentence.