Legal Question in Criminal Law in United States

I'm suspicious. Have you Googled this person's phone number to see if it's been reported as belonging to a scammer? This guy could be who he says he is, but there are several reasons to doubt it.

Buying stolen property is only a crime if the buyer knows at the time of purchase that it was stolen. Detectives know that. They also usually don't abuse their authority by acting as collection agents for family members -- especially by threatening to bring criminal charges. And they rarely communicate with suspects via text message.

Did the person claiming to be a detective even tell you his name and what police department he works for? If he didn't, then there's even more reason to be suspicious. If he did, call the department (using the same cell phone, so as not to reveal other contact info) and ask if they have a detective by that name. If they do, ask to speak with him. Tell him you're not prepared yet to talk about what happened, and that you want to verify he really sent the texts before seeking counsel. Make it clear that you're not refusing to cooperate, and that you just want to get legal advice first.

If he confirms that he sent the texts, look for a lawyer to help you. Don't discuss the factual or legal aspects of your case with the detective or other authorities in the meantime, whether during that initial call or afterwards. And be prepared to surrender the phone if it really was stolen.

Finally, if the detective says he didn't send the messages, ask him if he'd like to investigate a case of impersonating an officer and attempted extortion.

Good luck.