US border agents are rarely punished for their mistreatment or abuse of immigrants and American citizens, according to a new report by an immigration watchdog.

The American Immigration Council found that 97 percent of abuse complaints against US Border Patrol agents and Customs and Border Protection officers resulted in no disciplinary action after an investigation was completed.

The incidents that led to complaints range from physical beatings and “excessive use of force” to sexual abuse and racial profiling. In one of the more disturbing incidents, a pregnant woman miscarried after a Border agent kicked her in the stomach. Other immigrants complained that agents made them bare their breasts or be subjected to lengthy strip searches.

The survey found complaints against US border agents usually took years to resolve. The council reviewed 809 complaints filed from January 2009 to January 2012. Of those, only 485 were investigated and settled. The rest are still under investigation.

Of the 485 resolved complaints, only one resulted in a suspension, the worst infraction levied against agents, according to the report. Six complaints led to counselling, two led to court proceedings, two led to verbal reprimands, and two led to “written reports.”

Regarding the cases still “pending investigation, the average number of days between the date the complaint was filed and the last record date provided in the data set was 389 days,” the report said.

“This absolutely confirms the experiences of our border families and communities,” said Vicki Gaubeca, director of the American Civil Liberties Union’s Regional Center for Border Rights in New Mexico. “U.S. Customs and Border Protection is now the largest law enforcement agency in the nation, and yet this massive build-up of border enforcement resources has not been matched with adequate accountability and oversight.”

The two federal agencies, both under the Department of Homeland Security, have doubled in size in the last seven years, the report said, while complaints filed against their agents and officers have increased.

Customs and Border Protection did not comment to McClatchy news service on the report’s findings. The complaints analyzed in the report were accessed using a Freedom of Information Act request.

Physical abuse was the most common complaint, followed by “excessive use of force.” Seven complaints dealt with allegations of sexual abuse, including three allegations of forced sexual intercourse and four of inappropriate touching or forcing females to bare their breasts.

Yet 11 more instances that weren’t call sexual abuse by the agencies were similar in nature, including forced nudity, abusive strip searches, and more inappropriate touching.

Despite the rapid growth of the agencies and the rising amount of complaints against agents, the Department of Homeland Security does not offer statistics on complaints and how they are resolved.

An author of the report – Daniel Martinez, an assistant professor of sociology at George Washington University – said the findings only represent a small sample of abuse involved with Border agents. He told McClatchy hundreds of thousands of undocumented immigrants returned to their countries each year, and 10 percent claim they were abused while in US Border custody.

“This is just really scratching the surface of the true population,” Martinez said.

The report doesn’t include a September 2012 incident in which a Border Patrol agent jumped on the hood of an unarmed woman’s car and shot the woman nine times, according to an autopsy report.

In March of this year, a US border agent kidnapped and assaulted a woman, her daughter, and another girl late Wednesday as the three undocumented Honduran immigrants attempted to surrender. The agent committed suicide the next day.

Border Patrol agents have also killed at least 21 people in recent years, 10 of whom were shot for throwing rocks at agents.

These incidents of excessive force have been the subject of past investigations into Border agent behavior. A report by law enforcement experts – completed in February 2013 and still officially shielded from the public – chastised the Border Patrol for substandard investigations following cases where US agents fired their weapons. The review panel said that it could not determine whether the Border Patrol “consistently and thoroughly reviews” instances where deadly force was used.

The review was conducted by the Police Executive Research Forum, a non-profit research and policy organization in Washington. The group was offered Border Patrol case files on 67 shooting incidents from January 2010 to October 2012.

The researchers found evidence of border agents at times deliberately blocking a car’s path in order to shoot at drivers who were attempting to avoid arrest but were not a direct threat to anyone.

"It is suspected that in many vehicle shooting cases, the subject driver was attempting to flee from the agents who intentionally put themselves into the exit path of the vehicle, thereby exposing themselves to additional risk and creating justification for the use of deadly force," the report reads. There were times when "passengers were struck by agents' gunfire."