Investigators say Haley Rippetoe survived an intentional collision before she was attacked beside her damaged vehicle.

ERIE, Colo. — What first appeared to be a fatal overnight traffic crash became a murder investigation after officers found 28-year-old Haley Rippetoe outside her wrecked SUV and noticed evidence that did not match an accidental collision, according to prosecutors and an arrest affidavit.

The Weld County District Attorney’s Office has charged Rippetoe’s former boyfriend, 29-year-old Justin De Nileon Jr., with first-degree murder after deliberation. Authorities allege that De Nileon followed Rippetoe after she left work late June 20, deliberately struck her Nissan Rogue near Erie and attacked her after the vehicle rolled off the roadway. The charge is an allegation, and prosecutors must prove it in court. De Nileon is being held without bond at the Weld County Jail. His next announced court appearance is set for Sept. 2 in Weld County District Court.

Erie police were sent at about 1 a.m. June 21 to the intersection of Weld County Road 7 and Weld County Road 6. Officers found Rippetoe dead outside the driver’s side of her vehicle. They initially faced a scene that contained the signs of a serious crash: a damaged SUV, a body beside the roadway and evidence that the vehicle had left the pavement. But the amount and placement of blood caused officers to question whether the collision explained her death. Prosecutors later said the scene was not consistent with either a traffic-crash death or a person being thrown from a vehicle.

The arrest affidavit described several details that investigators considered suspicious. The driver’s seat belt remained fastened in its buckle, but the upper section appeared to have been cut cleanly with a sharp object. Additional marks suggested that someone had made more than one attempt to sever it. The driver’s window also had a large break and an oblong opening that investigators believed could have been made by someone trying to force access to the vehicle. Authorities allege those signs showed that the scene continued to develop after the impact rather than ending when the Nissan left the road.

Investigators also documented blood inside and outside the Rogue. According to the affidavit, blood was found on the driver’s seat, door panels and dashboard, as well as along the exterior driver’s side. Officers concluded that its location did not resemble injuries caused only by a rollover or an ejection. An autopsy provided another major change in the case. The medical examiner found multiple sharp-force injuries that were not consistent with a vehicle crash, the affidavit said. The injuries instead appeared to have been deliberately inflicted with a sharp instrument, according to investigators.

Police reconstructed the collision using damage at the site, surveillance footage and information about a second vehicle. They concluded that a white vehicle had struck Rippetoe’s Nissan and caused it to roll from the road. Authorities said the description and physical evidence were consistent with the white SUV driven by De Nileon. Surveillance cameras allegedly recorded that vehicle leaving the area after the crash. Investigators further alleged that Rippetoe had been followed from her workplace before the collision, turning what could have been treated as an isolated wreck into evidence of a planned encounter.

Rippetoe’s relatives began searching for her after technology in her phone reported a crash. Her brother and sister received automated iPhone notifications and drove toward the location identified in the alert, according to the affidavit. They reached the area and found officers already at the scene. Rippetoe’s father, Ryan Rippetoe, also received a crash notification. When police informed him that his daughter had been found dead, he immediately raised concern about De Nileon, telling officers that he did not believe the crash was an accident.

The father later told KUSA that his suspicion was tied to the history between his daughter and De Nileon. Rippetoe’s family told investigators that the relationship had included emotional and physical abuse. They described previous incidents in which De Nileon allegedly shoved her, threatened her and tried to force her vehicle from a road. Those accounts are allegations contained in the investigation and have not been tested at trial. They nevertheless gave detectives a reason to examine whether the crash was connected to the former relationship rather than an unrelated driving event.

Court-related records added urgency to that line of inquiry. De Nileon had been arrested in May in a separate case involving allegations that he kidnapped and assaulted Rippetoe. A protection order was in effect when she died, according to the affidavit and her family. The earlier charges did not establish that he committed the June killing, but they documented a recent legal conflict involving the same two people. Rippetoe’s father said his daughter had expressed doubt that a written order could protect her from someone willing to ignore it.

The investigation soon shifted toward De Nileon’s movements after the crash. The affidavit said phone records captured a call to his parents in which he sounded panicked. His parents contacted Broomfield police and requested a welfare check. Officers later encountered him at the family’s home, where he was allegedly concealing himself under a tent. Investigators said he had suspected blood on his clothing and cuts or abrasions on his hands. The amount of blood on the clothing appeared greater than what would be expected from his visible injuries, the affidavit said.

Those observations became part of a broader evidence trail rather than a single basis for the charge. Detectives compared the vehicles, reviewed surveillance recordings, studied the crash pattern, examined the damaged seat belt and window, collected biological evidence and considered the medical examiner’s findings. Prosecutors allege that the combined evidence shows De Nileon intentionally struck Rippetoe’s vehicle, gained access to her after the crash and killed her outside the SUV. The affidavit’s account represents the investigators’ version of events and may be challenged by the defense as the criminal case proceeds.

Authorities have not publicly described a confirmed motive, identified the sharp instrument believed to have caused Rippetoe’s fatal injuries or released a complete account of what happened between the collision and the arrival of officers. The district attorney’s office has also said it will not release additional information while the prosecution is pending. No plea or trial date was listed in the publicly announced case update. De Nileon remains presumed innocent unless he is convicted.

The next scheduled step is a Sept. 2 court appearance in Division 15. Until then, the charge remains pending, and the central allegation — that an apparent roadside crash was deliberately caused and followed by a fatal attack — will be examined through the court process.

Author note: Last updated August 3, 2026.