Prosecutors say evidence suggests he concealed her body and removed her belongings after her death.
LAKEWOOD, Colo. — A Colorado man has been charged with tampering with a deceased human body and tampering with evidence after prosecutors said his girlfriend’s body was found in a locked, narrow space between two commercial buildings weeks after she disappeared in 2025.
Brandon Mumma, 41, has pleaded not guilty in the case involving Jax Gratton, whose disappearance prompted searches across the Denver metropolitan area before her body was discovered in June 2025. Prosecutors allege that Mumma was the last known person with Gratton and later removed evidence connected to her death. Investigators have not charged him with homicide, and the exact cause of Gratton’s death remains undetermined.
According to prosecutors, Gratton was last seen by her roommate on April 15, 2025, when she left her apartment wearing a specific set of clothing. Investigators later determined that her final active phone session occurred during the early morning hours of April 16 and was linked to an internet address associated with a property on West Colfax Avenue in Lakewood. Surveillance footage allegedly showed Mumma entering a unit at that location shortly before 6 a.m. Prosecutors said he remained inside for more than an hour before moving his vehicle and returning with trash bags that were later discarded in a dumpster. Authorities contend those actions became a significant focus of the investigation after Gratton was reported missing and failed to contact friends or family. Family members and volunteers spent weeks searching for information about her whereabouts as the case drew growing public attention across the region.
Gratton’s body was discovered on June 6, 2025, in a secluded area between two buildings at 9655 and 9699 West Colfax Avenue. Prosecutors described the location as a four-foot-wide passageway that was locked from both ends and largely hidden from public view. Investigators said the area could not be easily accessed without a key. When her body was found, Gratton was reportedly wearing the same clothing she had on when she was last seen. Authorities also noted that an air-conditioning grate rested on part of her body. Prosecutors said investigators found damage to an air-conditioning unit below a second-story window associated with the unit where Gratton and Mumma had been seen. Officials have not publicly stated exactly how Gratton came to be in the enclosed area. They also have not alleged a definitive sequence of events leading to her death. The indictment focuses instead on allegations that evidence was concealed and that her body was moved after she died.
The investigation uncovered additional details that prosecutors say support their case. Authorities alleged that a male friend visited the apartment during the night and later left, leaving Gratton alone in the unit while she was asleep and under the influence of drugs. When investigators searched the location weeks later, they found that furniture present during April had been removed. Prosecutors said none of Gratton’s personal belongings, including her cellphone, were recovered. Investigators contend that evidence connected to her death was discarded to prevent discovery by law enforcement. At the same time, officials have acknowledged significant unanswered questions. An autopsy reportedly found no defensive wounds and no clear physical evidence establishing a specific cause of death. Medical examiners were unable to conclusively determine whether strangulation, aspiration, drug toxicity, or another factor caused or contributed to her death. The uncertainty surrounding those findings remains a central issue in the case.
Legal proceedings are continuing in Colorado’s First Judicial District. Mumma appeared in court and entered a plea of not guilty to the charges filed against him. Prosecutors have not announced additional charges, and court records indicate the case remains focused on allegations involving the handling of Gratton’s body and evidence after her death. Investigators continue to rely on surveillance footage, forensic findings, digital records, and witness statements as they prepare for future court hearings. The prosecution is expected to argue that Mumma’s actions after Gratton’s death demonstrate an effort to conceal evidence, while defense attorneys are expected to challenge those allegations and the conclusions investigators have drawn from the available evidence. The case has drawn attention because of the unusual location where the body was discovered and the unresolved questions surrounding how Gratton died.
The disappearance and discovery deeply affected Gratton’s family and friends, who spent weeks searching for answers before investigators located her body. Public attention intensified as details emerged about the hidden area between the buildings and the evidence described by prosecutors. Community members followed developments through court filings and public statements from authorities. While prosecutors have outlined a theory that evidence was removed and concealed, investigators continue to acknowledge that important facts remain unknown. The absence of a definitive cause of death has left lingering questions about Gratton’s final hours. As the criminal case moves forward, relatives and supporters continue to seek a fuller accounting of what happened between the night she vanished and the day her body was found.
The case remains pending. Mumma has denied the allegations through his not-guilty plea, and future court proceedings are expected to address forensic evidence, witness testimony, and the timeline investigators reconstructed from surveillance footage and digital records.