A Maryland couple are under investigation again by Child Protective Services after their children were found playing in a park near their home Sunday.

According to the 911 call, a man said he was approached by the children, ages 6 and 10, when they wanted to pet his dog.  He told 911 that their clothes were dirty and they were walking alone for 20 minutes, WRC reported.

It turns out the children the man was concerned about were Danielle and Alexander Meitiv's son and daughter.

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The Meitiv's made headlines earlier this year for using "free-range" parenting techniques that, as the family says, teaches children self-reliance and responsibility.

According to CNN, the couple dropped their children off at the park at 4:00 p.m. Sunday and told them to come home at 6:00 p.m.  When they were half an hour late, the parents starting looking.

They learned about the CPS intervention when the child advocates called the family.

CPS were called by police, which is standard procedure by Maryland law, according to CNN, when police are called on any possible case of child abuse or neglect.

Two hours after police first arrived, the children were not taken to their parents, but rather CPS offices in Rockville, Maryland.  Police were told CPS would contact the parents.

At 10:30 p.m., the Meitiv's and their children were reunited, more than five hours after police responded.

Danielle Meitiv took to Facebook to explain what happened.

The family was under investigation after police picked up the children on Dec. 20.  They were walking home, and someone reported them to police.  That case came to an end in March when the parents were found responsible for "unsubstantiated child neglect," a ruling when CPS "has some information supporting a finding of child neglect or has what appear to be credible reports that are at odds with each other or does not have sufficient information to reach a more definitive conclusion," WRC reported.

Despite the new charges, the parents told WRC that they will continue permitting their children to walk to and from their neighborhood park alone.