Question about a child custody issue?

My real problem is that my step-sister is an idiot and you can never trust anything she says. SO...I'm trying to verify some child custody law issues so I can give my step-dad a reasonable opinion.

Last week my step-sister (We'll call her Jane) told Dad that "Something" happened the night before and the father of her son (We'll call him John) took off with said son (who is 7, we'll call him Joe) and that she was going to have to "get the law involved"- note she hadn't Yet done so.

So, now a week later, she tells Dad that she called the police and they said they can't do anything because John's listed as Joe's father on his birth certificate (the were never married). She later said the police did go to the garage that John was living in and talked to him, but they decided that it was a good enough place and were just going to let John keep Joe.

Now she doesn't "know how to get him back" and no one will help her.

MY problems with this story are:

She just moved back into the state a month ago. The Only way he would have found out she was even here, let alone Where, was if She told him.

There is NO way the police just said no we can't help without first investigating something.

The police would also not make a custody decision.

So, in order for my step dad to believe that things couldn't have happened the way she said would be for me to know for sure what the law in this case would be.

He doesn't think the police would listen because Joe is John's son, so he has the right to take him. I say it's still kidnapping, and there's no way she called the police (since she likely has warrants still out for her)

They had never gone to court for any custody rights case, and are living in Utah