Brandon Mumma allegedly told police his girlfriend simply vanished after she passed out from drug use. More than a year later, prosecutors say they know exactly where Jax Gratton's body ended up—and how the 41-year-old Colorado man tried to cover it up.
Background
Jax Gratton was last seen alive on April 15, 2025, when she left her apartment in Lakewood, Colorado. Her roommate reported her missing after she failed to return home. What followed was months of searching by her family across the Denver metro area before authorities made a grim discovery on June 6, 2025.
Gratton's body was found wedged into an impossibly narrow space between buildings at 9655 and 9699 West Colfax Avenue in Lakewood—a gap measuring just four feet wide. The area was locked from both ends, required a key for entry, and featured a solid gate that completely obscured the location from public view.
According to investigators, Gratton was discovered lying on her side, wearing the same clothes she had on when she left her apartment in April. An air conditioning unit grate was found atop her lower body, and authorities noted significant damage to the AC unit directly below a second-story window at 9655 W. Colfax Avenue, Unit G.
The Investigation
Prosecutors with the First Judicial District Attorney's Office allege Mumma entered Gratton's unit around 5:55 a.m. on April 16, 2025—surveillance video captured his arrival. He remained inside until nearly 7 a.m., when he was seen on camera moving his vehicle to the north side of the building.
"He returned with trash bags, which he threw into a dumpster," the DA's office stated in a March 2026 press release announcing Mumma's indictment. "Mumma then left the area."
Investigators determined Gratton's last active phone session occurred in the early morning hours of April 16 using an IP address associated with that same Colfax Avenue location. By May 29, when authorities finally searched the unit, all furniture from April had been removed—and none of Gratton's personal belongings, including her cell phone, were ever recovered.
According to prosecutors, a male friend visited the unit at 12:14 a.m. on April 16 and left with Mumma at 1:43 a.m., leaving Gratton "alone and asleep under the influence of drugs." When Mumma returned hours later, he allegedly claimed Gratton was gone.
Mumma told police that Gratton had been under the influence of gamma-hydroxybutyrate, or GHB, and took too much that night. He claimed she passed out, began snoring, then started making gurgling noises and vomited. Mumma alleged he rolled her onto her side before leaving with his friend.
The autopsy report revealed methamphetamine, THC, citalopram, and trazodone in Gratton's system. While neither drug overdose nor strangulation could be definitively proven or ruled out, aspiration was listed as a possible cause of death. Investigators found no defensive wounds on the body.
Mumma has been charged with one count of tampering with a deceased human body and one count of tampering with evidence. He entered a not guilty plea during his court appearance last week.
Key Takeaways
- Brandon Mumma, 41, was indicted in March 2026 on charges of tampering with a deceased human body and evidence tampering
- Jax Gratton's body was discovered June 6, 2025, wedged into a 4-foot-wide space between buildings at 9655-9699 West Colfax Avenue in Lakewood
- Surveillance video allegedly shows Mumma entering the unit at 5:55 a.m. and later disposing of trash bags in a dumpster
- Gratton's phone, personal belongings, and furniture were never recovered from the apartment
- The cause of death remains undetermined; aspiration was listed as a possible contributing factor while strangulation could not be ruled out
What's Next
Mumma is due back in court on July 30. His trial is scheduled to begin in November. Investigators continue to examine evidence related to the case, and prosecutors have indicated additional details may emerge as they prepare for trial.
The investigation was conducted by the Lakewood Police Department in coordination with the First Judicial District Attorney's Office.