HENRICO COUNTY, Va. -- A North Carolina man and his 20-year-old biological daughter were arrested on incest and adultery charges after authorities discovered they had a baby together, reports CBS affiliate WNCN. According to the arrest warrants, the girl's father said they were planning to marry.

Katie Rose Pladl was born in 1998 to Steven Pladl and his wife, but was adopted out of state. When she turned 18 in 2016, Katie tracked down her biological parents and moved into their home west of Richmond, Virginia, where they lived with their two other children.

Months later, Katie's mother legally separated from her husband and moved out of the home. Her mother reportedly learned that Katie was pregnant with her husband's child in 2017, after reading it in the diary of one of her children. She called Steven, who confirmed that the two were having a baby, and that they planned to marry.

The couple's two other children also told Henrico County Child Advocacy Center that Steven was the father of Katie's baby boy.

Arrest warrants say that Steven Pladl told his other children to refer to Katie as their step-mother, according to WNCN.

Katie and Steven Pladl were each issued a $1 million bond and remanded to the Wake County Detention Center. Steven has since been released, but Katie remains in jail.