An American man has been arrested for incest after he dumped his wife and had a baby with his daughter who was given up for adoption.

Steven Walter Pladl, 42, and his biological daughter Katie Rose Pladl, 20, were arrested last week at their home in Knightdale, North Carolina, after Steven's estranged wife told police that he impregnated their daughter.

According to warrants, Katie was adopted out of state after she was born. When she turned 18 she used social media to find her biological parents, KRON 4 reports.

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Steven Pladl (left) and his biological daughter Katie Pladl (right) were arrested and charged with incest after they had a baby together

Katie Pladl, 20, was adopted out of state as a baby and reconnected with her parents when she turned 18

Shortly after Katie Pladl moved back in with her parents, her father Steven Pladl (pictured) and her mother legally separated. The wife told police that Steven had been sleeping in their daughter's room

In August 2016, Katie went to live with her parents and their two other children in their home near Richmond, Virginia.

The warrants state that Steven and his wife legally separated three months later, in November 2016.

The wife told authorities that the month she moved out of the home Steven had been sleeping on the floor of Katie's bedroom.

The wife also said that she learned her daughter was pregnant and that Steven was the father in May 2017 after reading one of her other children's journal.

According to the warrants, Steven had asked the two younger children to refer to Katie as their step-mom, although she was their sibling.

After learning about the pregnancy, the wife said she contacted her estranged husband and asked if he had impregnated Katie. He allegedly admitted the baby was his and said they planned to get married.

Katie posted an Instagram photo in July stating that she and Steven had gotten 'married', although they legally cannot do so.

Katie's baby boy was born in September, warrants revealed. The father and daughter were arrested in January at their North Carolina home

They have been charged with incest with adult, adultery, contributing to delinquency. Steven (pictured) bonded out of jail, but Katie remains behind bars

Police said at some point after May 2017, Katie and Steven moved to Wake County, North Carolina together. Arrest warrants were issued for them in November 2017 and they were arrested at their Knightdale home in January.

Authorities said when they were arrested a baby boy was with them. Warrants revealed the baby was born in September 2017.

The father and daughter are being held in the Wake County Detention Center pending extradition to Virginia. They have been charged with incest with adult, adultery, contributing to delinquency.

Steven and Katie were each issued a $1million bond. Steven bonded out of jail, but Katie remains behind bars.

It's not clear who the baby is in the care of.

Katie posted an Instagram photo announcing her 'marriage' to Steven, although they legally cannot wed