OKLAHOMA CITY - A federal judge sentenced Matthew Durham to 40 years in prison for molesting Kenyan orphans.

Durham traveled to Kenya several times as a volunteer; trips the government said were used to groom his victims.

A federal prosecutor called Durham's life a masquerade, saying Durham's trial exposed his true face.

Another missionary who worked with Durham said looking back, he too now sees the clues of Durham's double life.

“You know, Matthew, he put on a great persona as being a person that wanted to help these kids out of the good of his heart,” Tanner Bailey said.

As allegations surfaced of Matthew Durham molesting Kenyan orphans, Bailey began to question his friend and fellow Upendo Children's Home volunteer.

“Being with him, you know, I believed him. I saw the same thing that he showed everybody else,” Bailey said.

Bailey and Durham traveled to the Kenyan village of Juja together twice before the sexual assaults occurred. Bailey saw his friend then as a Christian with a big heart filled with love for the children.

Now, after Durham's sentencing, Bailey said he saw clues of Durham's inappropriate relationship with some of the orphans.

“Things that he would do, things that he would say. How he would play with the kids, it was different,” he said.

Bailey's last trip to Upendo was in December 2014, nearly six months after the assaults. By this time, federal prosecutors were at the children's home, investigating.

He said instead of being greeted with hugs, the children ran away in fear.

“Americans look the same to them and so having a buzz cut at the time and him having a buzz having the same build, the children ran from me when I got there. Which is heartbreaking because I love these kids,” Bailey said.

At sentencing, Upendo's founder Eunice Menja said "Durham stained Upendo with sexual abuse."

In addition to prison time, Durham will be a lifelong registered sex offender and on supervised released.