A 14-year-old girl whose 22-year-old husband is charged with sexually assaulting a minor has given birth to their daughter, and the man said he plans to plead not guilty in the case.

The girl became pregnant when she was 13, and her mother gave permission in May for Matthew Koso to take the girl to Kansas to marry.

Nebraska requires people to be at least 17 before they can marry. But Kansas does not have a minimum age as long as both parents or guardians approve or the marriage is approved by a judge, said a spokesman for Kansas Atty. Gen. Phill Kline.

Nebraska Atty. Gen. Jon Bruning has charged Koso with first-degree sexual assault, punishable by up to 50 years in prison if he is convicted.

“Of course the marriage is valid … but it doesn’t matter,” he said. “I’m not going to stand by while a grown man … has a relationship with a 13-year-old – now 14-year old – girl.”

Koso told the Lincoln Journal Star he expected to plead not guilty at his arraignment on Tuesday.

Bruning has said Koso is a friend of the girl’s half-brother and began a relationship with her when she was 12.