The litany of abuses is long.

In July 2011, four Uruguayan peacekeepers and their commanding officer allegedly gang-raped a Haitian teenager. The men also filmed the alleged attack on their phones, which went viral on the internet. The men never faced trial in Haiti; four of the five were convicted in Uruguay of "private violence," a lesser charge. Uruguayan officials said at the time that it was a prank gone wrong and that no rape occurred.

The following year, three Pakistanis attached to the U.N.'s police units in Haiti were allegedly involved in the rape of a mentally disabled 13-year-old in the northern city of Gonaives.

U.N. officials went to Haiti to investigate, but the Pakistanis abducted the boy to keep him from detailing the abuse that had gone on for more than a year, according to Peter Gallo, a former U.N. investigator familiar with the case.

Finally, the men were tried in a Pakistani military tribunal, and eventually sent back to Pakistan. In theory, the tribunal could have allowed for better access to witnesses, but it's unclear whether any were called. The Pakistani authorities also refused to allow the U.N. to observe the proceedings. In the end, one man was sent to prison for a year, according to Ariane Quentier, a spokeswoman for the Haiti mission.

"It's an indictment of how the whole U.N. system works," Gallo told the AP.

Pakistan's military has refused several requests for comment on the case.

U.N. data during the 12-year period reviewed by AP is incomplete and varies in levels of detail, particularly for cases before 2010. Hundreds of other cases were closed with little to no explanation. In its review, the AP analyzed data from annual reports as well as information from the Office of Internal Oversight Services.

This image from a U.N. internal investigation document shows shipping containers at the U.N. military base in Jacmel, Haiti, where a girl, 14, said she had sex with "Commandants."

In the wake of the child sex ring investigation, a team of Sri Lankans spent two weeks in Haiti in October 2007. They interviewed only 25 soldiers out of more than 900 in the country and concluded that just two Sri Lankan corporals and one private had sex with two "young" victims. Three soldiers denied sexual encounters but were suspected of lying, according to the U.N. investigation report.

For six months, the Sri Lankan army and the government declined to respond to AP's questions about the 2007 case. Instead, officials first dodged repeated queries, then gave vague assurances that the scandal represented an isolated incident. Last month, the Sri Lankan government acknowledged its military had conducted inquiries into just 18 soldiers it said were implicated, and that "the U.N. Secretariat has acknowledged in writing, action taken by the Government, and informed that the Secretariat, as of 29 September 2014, considers the matter closed."

Some of the peacekeepers involved in the ring were still in the Sri Lankan military as of last year, Sri Lankan military officials say. The United Nations, meanwhile, continued to send Sri Lankan peacekeepers to Haiti and elsewhere despite corroborating the child sex ring.

Sri Lankan Defense Secretary Karunasena Hettiarachchi defended the troops, saying, "People are quite happy and comfortable with the peacekeepers."

___

Above a rusty bench at an abandoned bus stop in the village of Leogane hangs a sign that reads, "Constructed by the 16th Sri Lanka Peacekeeping Battalion." It's one of the few physical reminders of the battalion's mission — along with children fathered by U.N. personnel.

Marie-Ange Haitis says she met a Sri Lankan commander in December 2006 and he soon began making night-time visits to her house in Leogane.

"By January, we had had sex," she said. "It wasn't rape, but it wasn't exactly consensual, either. I felt like I didn't have a choice."