DALLAS (AP) — On a summer morning last year, FBI agents arrived at the home of a prominent real estate developer in Austin and began scouring the palatial French-style chateau for documents, videos and photographs as part of an investigation that remains under wraps.

Nate Paul alleges in a criminal complaint obtained by The Associated Press that the agents detained him during their hours-long search and repeatedly refused to show him their warrant. He wrote in the complaint that the warrants eventually turned over to his lawyers had been tampered with.

Meanwhile, details of the FBI probe remain undisclosed.

The search of Paul's home set off a series of maneuvers by private attorneys and state and federal law enforcement that recently burst into public view with Texas Attorney General Ken Paxton’s top deputies accusing the Republican of crimes tied to his investigation of Paul’s claims. Paxton has acknowledged knowing the developer, but the nature of their relationship remains unclear.

And exactly what Paul wanted investigated was not previously public. The details of his complaint deepen questions about its path to the office of an attorney general who got a $25,000 campaign contribution from the developer in 2018.

“Usually, you don’t take it to the state authorities to investigate the feds,” said Toby Shook, a prominent Dallas criminal defense attorney and former county prosecutor.

In the June request for an investigation, Paul accused the agents, federal prosecutors, a judge and other officials of illegally seizing his property and violating his rights. He claimed they broke state laws against tampering with government documents and “official oppression.”

The FBI and federal prosecutors in West Texas declined to comment. Several legal experts who reviewed Paul’s complaint were skeptical that it shows crimes by law enforcement.

Paul, who's fighting with creditors over millions in delinquent debt, suggested the search warrants for his home and offices were monkeyed with and obtained based on “false information. He alleged the warrants were sent to his lawyers hours and days after the 2019 searches and don’t match the documents filed in court.

Paul has not been publicly charged with any crime. His lawyer and Paxton's office did not respond to questions Thursday.

Paxton's hiring of an outside attorney to investigate Paul's claims led his seven top deputies to report the attorney general to the FBI for alleged abuse of office, bribery and other crimes. Paxton dropped the case into Paul's claims this month, but the fallout has deepened political, and possibly legal, trouble for the attorney general.

Paxton rose to national prominence during his time in office but has spent most of it maintaining his innocence in the face of separate criminal charges. On Thursday, an appeals court put on hold a decision to send the securities fraud case against Paxton back to his home county north of Dallas

Legal experts who reviewed Paul's claims said that, if true, they could be obstacles in a potential prosecution. They said some of the behavior described as outrageous in the complaint is actually typical, while other actions might warrant scrutiny but were unlikely to be criminal.

“What they’re complaining about was obviously very uncomfortable," said Laurie Levenson, a professor at Loyola Law School and former federal prosecutor. “But the type of misconduct that gets attention is when people are hurt, when there’s ransacking, when there are no warrants.”

Paul claimed the FBI seized material privileged by attorney-client confidentiality and things beyond the scope of the search warrants. He said some warrants weren't disclosed and the metadata of the ones sent to his lawyers showed they were edited after the search began, although it's unclear what that indicates.

The federal judge who Paul said authorized the warrants, Mark Lane, did not respond to a request for comment.

Experts said Paul's claims could be grounds for a civil suit or to get evidence tossed in a potential prosecution. Some said they might merit outside scrutiny of the investigators.

“If what he’s saying is true, it shows some problems,” said Daniel Medwed, a professor at Northeastern University School of Law. He said Paxton's actions raise serious questions, regardless of the merits of Paul's claims.

Mike Snipes, a former state and federal prosecutor and retired Texas judge, said the state has no jurisdiction over Paul claims. The developer's remedy would be in federal court, Snipes said, but the people he's accused would have immunity because they were acting in their official capacity.

Snipes called the complaint “frivolous” and speculated that Paul was “just trying to see if he can scare people off, into not conducting an investigation.”