In April 2011, a Border Patrol agent was ordered to undergo counseling after an immigrant filed a formal complaint charging that the agent had slammed the man's head against a rock near Tucson.
In August of that year, an immigrant who was arrested near El Paso accused a Border Patrol agent of stepping on his face and kneeing him in the ribs after he was handcuffed. Internal affairs officers investigated the case, but took no action.
That same month, an unaccompanied minor complained that a Border Patrol agent "hit him on the head with a metal flashlight 20 times, kicked him 5 times, pushed him down a hill." The case was still under review more than two years later.
The vast majority of complaints lodged against Border Patrol agents operating within 100 miles of the Southwest border result in no disciplinary action or are still pending after many years, according to newly released documents from the agency's office of internal affairs.
The records suggest little accountability for alleged kicking, beating, sexual abuse and other mistreatment of detainees in custody and other immigrants by members of one of the nation's largest law enforcement agencies, one that has come under growing fire for its use-of-force policies and lack of transparency.
Only 13 of 809 abuse complaints sent to the agency's internal affairs unit between January 2009 and January 2012 led to disciplinary action, the records show.
Most of the 13 were ordered to undergo counseling, the records indicate. Forty percent of the total claims were unresolved more than two years after being reported. Some cases remain open after four years.
U.S. Customs and Border Protection, which runs the Border Patrol, does not routinely notify people about the outcome of their complaints.
The records provide the most detailed public view to date of alleged mistreatment and misbehavior by Border Patrol agents. The Border Patrol has often rebuffed requests from the media and members of Congress for information about its agents' use of force.
"This is another disturbing report shedding further light onto what we have known for far too long: We need accountability at Border Patrol," Sen. Robert Menendez (D-N.J.), chairman of the Senate Foreign Relations Committee, said Friday.
The 44-page list was obtained by the American Immigration Council, an advocacy group, through a Freedom of Information Act request and shared with The Times.
The records do not include allegations that were referred to a separate office of civil rights and civil liberties, the Justice Department, the Office of Inspector General or other federal offices empowered to investigate wrongdoing by border agents.
It does not include at least 15 cases in which Border Patrol agents shot and killed people on the border in that three-year period, for example. The agency has declined to say whether any of those agents faced disciplinary action or criminal charges.
The new details come as Secretary of Homeland Security Jeh Johnson has ordered a review of the immigration enforcement system to see whether changes can be made to ensure that immigrants are treated more humanely.
R. Gil Kerlikowske, who took over Customs and Border Protection in March, said Friday that he would focus new attention on the use of force.
Border agents and officers "strive to treat each of the over 1 million people we come into contact with each day with the respect they deserve," he said in a statement. "All allegations of misconduct are taken seriously, and if warranted, [are referred] for appropriate investigative and/or disciplinary action to be taken."
Shawn Moran, the vice president of the Border Patrol agents' union, defended the agents' actions and denied that abuse was widespread or officially condoned.
"There will always be a few bad apples," Moran said, adding that if Border Patrol officials released more information about abuse investigations, the public would be reassured that the vast majority of agents are acting appropriately.
He said the number of complaints is relatively small when compared with the hundreds of thousands of people apprehended trying to cross the border each year.
"Agents are doing a good job in terms of the sheer number of arrests they make," Moran said.
Moran said some people being arrested will allege abuse in an effort to slow down their deportation from the country.
"This is not a sterile business. It is law enforcement. Not everybody goes along peacefully," he said.
But critics of the Border Patrol say that the records show a pattern of brutality and impunity at the Border Patrol.
"There is no oversight and there is no accountability for agents who break the law," James Lyall, a staff attorney for the American Civil Liberties Union of Arizona, said in a telephone interview from Tucson.
"If a counseling session is the worst you will face, no wonder abuse goes unchecked," Lyall said.
Daniel E. Martinez, an assistant professor of sociology at George Washington University who studies unauthorized migration, believes that Customs and Border Protection has not appropriately trained or disciplined new agents coming into the force.
"People are not being held accountable for their actions," he said.
Martinez said a survey he conducted found that 1 in 10 migrants reported being physically abused, punched, kicked or slapped by Border Patrol agents when they were found illegally crossing the border.
Many investigations in the database are still pending four years after they began.
On April 6, 2010, an immigrant claimed that a Border Patrol agent "stomped" him on the back of his neck while being restrained in the Rio Grande Valley in Texas. The case has not been resolved.
On April 22, 2010, an immigrant alleged that the humerus bone in his upper left arm was broken when a Border Patrol agent from Campo Station in Pine Valley, Calif., handcuffed him. The investigation is still pending.
The American Immigration Council, the ACLU and other organizations have recommended the creation of a single, centralized complaint form and a toll-free number that could be displayed at checkpoints, ports of entries and on Border Patrol vehicles.
Border Patrol Chief Michael Fisher issued new rules in March that expressly restricted agents for the first time from shooting at moving vehicles and at people throwing rocks if they do not pose a serious threat to agents.
The directive was issued after the Los Angeles Times obtained a study of 67 deadly force incidents involving Border Patrol agents. The study by the Police Executive Research Forum, a group of law enforcement experts, sharply criticized the Border Patrol for a lack of diligence in investigating incidents involving use of force.
The Border Patrol has grown to more than 21,000 agents, more than double its size in 2004. At the same time, the level of experience of agents in the field has declined, according to a 2010 report by the Congressional Research Service.