TULSA, Oklahoma - Police arrested the fifth person involved in a child sex abuse case after she turned herself in.

David Lewis, the father of two of the abused children, said he learned about the arrests on the News On 6 Facebook page. He said he hopes to reunite with his children.

"I don’t understand why they didn’t call me,” Lewis said.

He said knowing his children are a part of a child sex abuse case is hard. Even with his wife’s support, he couldn’t stop from showing emotion.

"I'm blaming myself every hour because in my mind, if I had taken them when I left this would have never happened,” Lewis said.

Lewis said he and his children’s mother broke up years ago. News On 6 isn’t naming her to protect the children’s identity.

For the past three years, Lewis said it’s been a struggle to see his kids – even with split custody.

“She had to talk to Brian [Campbell] to see what Brian said before she would do anything,” Lewis said.

The answer each time: “Brian said ‘no.’”

Campbell is the man police say courted the women to get close to their children. Now, Campbell and the four mothers are in jail.

Lewis said getting his children back is a challenge.

“It just tears me up. And the fact that DHS never tried to contact me about taking the kids when they took them from her,” Lewis said.

DHS officials aren’t allowed to talk about the case, but generally, when children are removed, the offending guardian gives a suggestion on which relatives could take the children. If the background check is clear, the children are then placed.

Lewis said currently, their maternal grandmother has the children. He said since the children are undergoing major counseling, he’s been advised to hold off on fighting for them.

“I see this stuff on the TV all the time and never thought my kids would be wrapped up in something as sick and as vile as this."

Lewis said he plans to continue talking with child welfare representatives to see what other options he has for getting his kids back.