On Sept. 28, 2012, in an apartment in suburban Chula Vista, California, a suburb of San Diego, Alvarado opened the door to see Tackett and another Border Patrol agent dressed in plain clothes. The men had an arrest warrant for a man with immigration violations, but the warrant did not allow the agents to search any homes or vehicles. Alvarado, who had no connection to the warrant, decided to leave.

According to details of the police investigation that followed, Alvarado hit Tackett with her car as she drove away. Afraid for his life, the agent then fired his pistol at her while hanging from the hood of her car, shooting her nine times. Other witness accounts contend that Tackett jumped on the hood of Alvarado’s car to stop her from leaving after another Border Patrol agent shattered her window. Panicked, Alvarado then drove a short distance and stopped; Tackett jumped off the car and as Alvarado began backing up, he shot her, walking toward the car as he fired.

Tachiquin says Tackett — who had a dubious work history long before joining Border Patrol, according to the wrongful-death lawsuit and the wrongful termination suit Tackett filed — should never have been hired. Tackett joined the Imperial County Sheriff’s Department in the summer of 2000. In three and a half years in the department, he racked up at least five reprimands and suspensions for misconduct.

During one of four motor-vehicle accidents in which he was involved, Tackett lost control of his patrol car and rolled it over while responding to a call. In a separate incident, his supervisors charged him with ignoring orders and providing false information to investigators. He was also accused of locking a suspect in a car without air conditioning and with all the windows closed on a hot day. On another occasion, Tackett searched a suspect’s hotel room without first gaining a warrant or acting on sufficient legal grounds. The district attorney subsequently dismissed the case against the suspect, saying that the Fourth Amendment violations were “almost too numerous to list.”

In yet another incident, Tackett was ordered to investigate a possible hit and run. He ignored orders to wait for local police backup before approaching the suspect’s car, resulting in an altercation with the driver. His supervisor later said that Tackett “instigated the incident” and “unnecessarily exposed himself and the Sheriff's Department to a citizen complaint or civil suit.”

In December 2003, Tackett resigned before the sheriff’s department could fire him. He later filed the wrongful termination suit, saying that Latino deputies received preferential treatment. (Tackett is white.) He also alleged that the department had accused him of misconduct for taking action against well-connected individuals. His lawsuit was dismissed on a summary judgment.

After he left the sheriff’s department, Tackett worked for two years as an assistant to former Congressman Duncan Lee Hunter. Alvarado’s family alleges that Hunter’s office helped Tackett get the job with the Border Patrol in 2006. That was the same year the agency received orders to double its numbers.

As the Border Patrol grew, people living near the border with Mexico say, the agency took on an ever-expanding role within their communities — but without the same oversight as local police departments. Citizens now reported seeing Border Patrol officials, restricted to operating within 100 miles of the border, at interior checkpoints and patrolling in suburban neighborhoods.

“What is the true identity of Border Patrol? Is it a military force that’s put up to a different set of standards? Is it a policing force that would be required to operate under the same requirements that any police force would? Having it be vague and not having a clear answer around this question after such a huge spurt of growth creates opportunity for chaos,” says Juanita Molina, executive director of Border Action Network, a human-rights group in Tucson, Arizona.