Updated at 7 p.m. Friday with more details from the lawsuit and comments from attorneys.

The family of a 26-year-old accountant slain in his home by a Dallas police officer who said she mistook his apartment for hers filed suit Friday against the city and the cop who killed him.

Amber Guyger was off duty but in uniform when she shot and killed Botham Jean on Sept. 6 at South Side Flats, down the street from Dallas police headquarters in the Cedars neighborhood.

Amber Guyger was arrested three days after Botham Jean was killed and lost her job 15 days after that. (Kaufman County Sheriff's Office)

The federal lawsuit says Guyger used excessive force and violated Jean's constitutional and civil rights and that Dallas Police Chief U. Renee Hall, the City Council and city manager "failed to implement and enforce such policies, practices and procedure for the DPD that respected Jean's constitutional rights."

Guyger, 30, was charged with manslaughter three days after Jean's death. She was later fired from the Dallas Police Department.

Interim City Attorney Chris Caso said Friday evening only that he was aware of the lawsuit and had no comment.

Guyger's attorney in the criminal case, Robert Rogers, also declined to comment. He has previously said Guyger is "completely devastated by what happened" and described the shooting as "a tragic mistake."

Although Guyger wasn't on the clock at the time of the shooting, a court could find the city liable if she used her authority as a police officer when she shot Jean. But the city will certainly argue Guyger acted as a startled resident returning to what she thought was her home.

The lawsuit was filed by Jean's parents, Allison and Bertrum Jean, who live on the Caribbean island of St. Lucia, and his sister, Allisa Findley of New York. Jean grew up in St. Lucia but came to the U.S. for college at Harding University in Arkansas and then found a job as an accountant at PricewaterhouseCoopers in Dallas. He planned to one day return home, where his mother is a former government official, to run for prime minister.

The lawsuit will most likely be put on hold until the criminal charge against Guyger winds its way through criminal court. A grand jury could indict her for manslaughter, murder or another charge. It could also decide she should not be charged with a crime.

Last week, Allison and Bertrum Jean flew to Dallas and met with District Attorney Faith Johnson. The Jeans have been upset with how Dallas police and the Texas Rangers have handled the case but said they are comforted and satisfied with how prosecutors are handling the case.

'Shoot first'

The couple's lawsuit argues that better training by the Dallas Police Department could have prevented Jean's death.

"By simply following proper police procedures and the best police practices and not the protocol of the DPD to 'shoot first and ask questions later', Defendant Guyger would have not shot Jean," the lawsuit states. "Essentially, Officer Guyger was ill-trained, and as a result, defaulted to the defective DPD policy: to use deadly force even when there exist no immediate threat of harm to themselves or others."

Dallas police have a "pattern, practice, history and custom of using excessive force against minorities, including approaching them with guns drawn," according to the suit. The lawsuit says the department has said it would change its policies over the years but failed to do so.

Botham Jean grew up in the Caribbean but moved to the U.S. for college and to Dallas to start a career. (via Instagram)

The chief and the City Council failed "to implement the necessary policies and the (de facto) implementation of unconstitutional policies, causes Jean to experience an unwarranted and excruciating physical and mental anguish before his ultimate death. For these civil rights violations and other causes of action discussed herein, Plaintiffs seek answers and compensation for their respective damages."

The lawsuit does not ask for a specific dollar amount.

The Jeans want their lawsuit to bring about changes in how police officers are trained, said attorney Lee Merritt, who represents Jean's family, along with Daryl Washington and Benjamin Crump.

"They want accountability," Merritt said. "Part of the goal of civil lawsuits is for the monetary damages to make the defendants take steps to prevent this in the future."

Merritt said the Jeans aren't holding themselves as experts to say what that training should be. But, he said, "a man sitting in his home should not be killed."

Warning signs

The lawsuit raises questions about why Guyger didn't notice she was on the wrong floor and in the wrong apartment. Jean lived on the fourth floor, and Guyger lived directly below him. Jean had a red mat in front of his door. Guyger did not.

Guyger told law enforcement that Jean's door was unlocked and ajar. Jean's family has said he would have locked and shut his door.

The officer also failed to notice, the lawsuit says, that her key did not chime as it would have if she inserted it into the electronic lock on her door.

Allison and Bertrum Jean hold a photo of their son Botham Jean at their home in St. Lucia. Botham Jean was shot and killed in his apartment by off-duty Dallas police officer Amber Guyger. (Vernon Bryant / Staff Photographer)

"The door would have not produced the identical chime Defendant Guyger hears daily at her apartment, which would indicate to a reasonable police officer that she had entered her key into the wrong keyhole if that is indeed what happened," the suit says. "In fact, the light above the keyhole would have flashed red, indicating to Defendant Guyger that her key did not match the lock she was then attempting to access."

Guyger arrived at Jean's door around 10 p.m. as Jean sat on the couch. The lights were out except for the football game he was watching on TV. The lawsuit says light from the hallway and television should have provided enough light for Guyger to see she was in the wrong place.

"After opening the door to Jean's apartment, Defendant Guyger stated in an interview with the Texas Rangers that she drew her service weapon and began issuing verbal commands to Jean, who was lawfully in his apartment," the lawsuit says. "Jean attempted to comply by slowly arising from his seated position. Without any lawful justification to do so and not asking the questions that a reasonable well-trained officer would have, Defendant Guyger fired upon Jean, striking him in the chest although he was unarmed and not attempting to harm her or any other person."

The lawsuit says Guyger could have shut the door and called police for backup while she waited outside the apartment or used less deadly tactics.

After Guyger shot Jean in the chest, the lawsuit says, she did not give Jean first aid. Police have said she did try to help him.

The lawsuit says the department did not treat Guyger like any other citizen. The shooting was initially investigated by Dallas police as an officer-involved shooting.

She was, the lawsuit says, not immediately arrested and allowed to "roam about the crime scene," make phone calls and allowed to re-enter Jean's apartment and go to her own home.

Staff writer Robert Wilonsky contributed to this report.