Published: June 11, 2013 at 3:03 PM

WASHINGTON, June 11 (UPI) -- Lawmakers, rights groups and families of victims say they want more accountability for the Border Patrol after agents were blamed in the deaths of 15 people.

Some of the shootings, all since January 2010, were prompted by rocks being thrown at Border Patrol agents from the Mexican side of the border, The New York Times reported Monday.

Agents last October shot and killed a teenage boy who was among a group of people in Nogales, Mexico, throwing rocks at Border Patrol officers on the U.S. side of the border.

In none of the cases has a single agent been criminally charged with lethal use of force. The parent agency, Customs and Border Protection, won't say if anyone has been disciplined.

Charles K. Edwards, acting inspector general for the Department of Homeland Security, began a review of use of force by border agents after 16 members of Congress criticized the "appalling behavior" of agents in San Diego in which a restrained man died after being hit with a Taser several times.

CBP also commissioned an analysis and an agency spokesman said the findings, which have not been made public, are now being reviewed.

Sen. Richard Durbin, D-Ill., has inserted a provision in the immigration bill now under consideration in the Senate that would require DHS and the Justice Department to develop policies on reporting use of force, investigating complaints and disciplining agents.

Shawn Milton, vice president at large of the union that represents 17,000 Border Patrol agents, said use of force by agents was sometimes necessary to protect themselves.

"When you look at the number of apprehensions we have every year, the number of use-of-force incidents is minuscule," he added.