Story highlights Matthew Lane Durham, 19, sexually assaulted as many as 10 children, authorities say

His alleged victims, boys and girls, were from 4 to 9 years old, court documents say

Durham's lawyer, Steven Jones, said his client denies the allegations

Jones said that Durham's passport was withheld and he was coerced into confessing

In April, Matthew Lane Durham volunteered his time at a children's home in Nairobi, Kenya, which recruited people from Oklahoma churches to provide food, housing and clothes to neglected kids in the African nation.

But federal prosecutors accuse the 19-year-old Edmond, Oklahoma, resident of performing sexual acts on as many as 10 children during his time there.

Durham was arrested on Thursday, July 17, on charges that include traveling to a foreign place to engage in illicit sexual conduct with minors and aggravated sexual abuse with minors, according to a criminal complaint filed in U.S. District Court in Oklahoma.

Durham allegedly engaged in sexual activity with victims, boys and girls from 4 to 9 years old, according to the complaint. At least one victim is HIV positive.

Durham's lawyer, Steven Jones, said his client denied the allegations and said he was essentially coerced into confessing to get his passport back. He said Durham was held at a house, for a time without food, and subjected to a "pseudopsychological good cop, bad cop" routine with "elements of religion and manipulation."

But the complaint said that when Durham arrived at the school in Nairobi in late April, he requested to stay at an "overflow bunk" in the school rather than off-site facilities with sponsor families to be in a "better position to assist the children."

In early June, a school caretaker began to notice odd behavior between Durham and the children, including "lingering embraces" and "lying beside some of children on their beds" at night, according to the complaint.

The caretaker told authorities that she asked the children about her suspicions, and they recounted sexual episodes with Durham, according to court documents. She brought her concerns to the founder of the school, an American from the same Oklahoma town as Durham.

Durham initially denied the allegations when confronted by the founder, but then "admitted to be struggling with homosexuality and child pornography," the complaint says. The founder moved the teen to a temporary house away from the children and held his passport.

The school's founder told authorities that five days later, she confronted Durham again and videotaped him confessing to having performed sexual acts and raping some of the victims, according to the complaint. Durham's descriptions of the events had become so "unbearable for her to hear" that she had him write and sign the confession, which she later turned over to the U.S. Embassy officials.

The founder also alerted federal officials in the United States as well local police, who told her that she could not legally withhold the suspect's passport, according to court documents.

The passport was returned to Durham, and he flew back home to Oklahoma with a ticket purchased by his parents, the complaint said.

The school, founded by an American citizen, recruits volunteers from the Oklahoma church community and provides food, housing and clothes to neglected children in Nairobi, according to the complaint.

The teen had volunteered at the school three previous times since June 2012. On those occasions, he was housed with sponsor families, the complaint said.

Durham, who appeared in court Friday, was being held without bond, according to a statement from the FBI Oklahoma City Division . A preliminary hearing is scheduled for August 1.

If convicted, Durham faces up to life in prison, according to the statement.