(CNN) The parents of Gabby Petito filed a $50 million wrongful death lawsuit against the Moab City Police Department on Thursday alleging its officers were negligent in their interactions with the 22-year-old and her fiancé Brian Laundrie two weeks before her death last summer.
"The purpose of this lawsuit is to honor Gabby's legacy by demanding accountability and working toward systemic changes to protect victims of domestic abuse and violence and prevent such tragedies in the future," attorney James W. McConkie said in a statement.
The lawsuit accuses the department and its officers of failing to follow the law and failing to protect Petito during an investigation into a domestic disturbance in August -- just weeks before Laundrie killed her. The lawsuit states that officers improperly determined Petito was the primary aggressor in the interaction and misapplied Utah's laws related to domestic abuse. It also accuses the police department of failing to properly train its officers in these issues.
In a news conference Thursday, her parents said they filed the suit to ensure that police make these changes to help other abuse victims.
"No one here, the four of us, don't want to be here. We'd give it up in a second if she was back," said her father, Joseph Petito.
"We feel we need to bring justice because she could have been protected that day," said Nichole Schmidt, her mother. "There are laws put in place to protect victims, and those laws were not followed, and we don't want this to happen to anyone else."
The City of Moab issued a statement Thursday denying responsibility for her death and saying it would defend against the lawsuit.
"The death of Gabrielle Petito in Wyoming is a terrible tragedy, and we feel profound sympathy for the Petito and Schmidt families and the painful loss they have endured. At the same time, it is clear that Moab City Police Department officers are not responsible for Gabrielle Petito's eventual murder," the city said.
The city said its officers "acted with kindness, respect, and empathy toward Ms. Petito" during their interaction.
"The attorneys for the Petito family seem to suggest that somehow our officers could see into the future based on this single interaction. In truth, on Aug. 12, no one could have predicted the tragedy that would occur weeks later and hundreds of miles away, and the City of Moab will ardently defend against this lawsuit," the city said.
Petito was 22 when she and her fiancé, Laundrie, 23, embarked on a road trip through the American West last summer, documenting their #VanLife experiences online in idyllic, sun-drenched posts.
Despite their online appearance, their relationship was rocky and at turns violent. Petito was reported missing after Laundrie returned to his parents' Florida home on September 1 and her parents were unable to contact her, sparking a nationwide hunt that became a fascination for online sleuths.
Her body was found several weeks later in Grand Teton National Forest, and a coroner ruled she died by strangulation. Laundrie subsequently went missing in a Florida nature preserve, and his body was found in mid-October alongside a notebook in which he admitted killing her.
In August, Petito's parents filed a notice of claim against the police department, the first step in initiating a lawsuit. Her parents have also taken legal action against Laundrie's estate and have filed suit against his parents, accusing them of causing emotional distress by failing to act during the search for Petito.
The 35-page lawsuit filed Thursday is based on the traffic stop last August after officers were informed that a witness "had seen Brian assault Gabby."
Police pulled over their vehicle -- a white Ford van -- after it exceeded the speed limit, abruptly left its lane and struck a curb, according to a police report.
Footage recorded by police body cameras shows Moab, Utah, police officers talking to Petito and Laundrie, who admitted having a fight in which Petito said she struck her fiancé first. Officers noticed Petito had cuts on her face and arm, and she "demonstrated how Brian had violently grabbed her face during their altercation," telling police Laundrie "gets frustrated with me a lot."
But Petito also "displayed the classic hallmarks of an abused partner," the notice of claim says, by taking blame for the incident. The officers "did not press further," the notice says.
According to the family's claim, a photo taken at the time, which has not been made public, "shows a close-up view of Gabby's face where blood is smeared on her cheek and left eye, revealing the violent nature of Brian's attack."
Laundrie told police the couple had been under increasing stress. He admitted to pushing Petito away when she tried to slap him and to taking her phone, claiming he didn't have one -- and was afraid that she would leave him. However, later in the interview, he took out his own phone and gave officers his number, the suit says.
Despite the cuts and Laundrie's inconsistencies, one of the officers said Petito must be booked into jail since, under the domestic violence statutes of Utah, she was considered the primary aggressor and Laundrie the victim.
Both Petito and Laundrie objected, and the officers eventually agreed not to charge Petito if she and Laundrie agreed to spend the night apart.
A review of the Moab Police Department's handling of the incident by an independent investigator -- a captain with the police department in Price, Utah, about 115 miles away -- recommended the two officers who responded be placed on probation, saying they made "several unintentional mistakes" -- namely failing to cite anyone for domestic violence, though there appeared to be only sufficient evidence to charge Petito.
The investigative report, released in January, recommended new policies for the department, including additional domestic violence training and legal training for officers.
The city at the time did not address any potential discipline for the two officers but said it "intends to implement the report's recommendations" on new policies for the police department, including additional domestic violence training and legal training for officers.