At a military base outside Bangkok, soldiers stand guard over Buddha statues, showcases of Rolex watches and some very expensive French wine — a $4,000 bottle of Petrus and choice vintages of Dom Perignon.

It all belonged to a man who led Thailand's equivalent of the FBI and is now serving 31 years in prison on corruption and other convictions. A four-day auction that opened Thursday features a small portion of the 27,000 items police say they seized from longtime Central Investigation Bureau head Lt. Gen. Pongpat Chayapan.

Authorities have expressed shock over Pongpat's misdeeds, but the Thai public is mainly astonished that someone so powerful actually got caught. Those who study corruption in Thailand say the case is a window into the graft that pervades Thai society and is particularly prominent in the police force.

Pongpat's case is interwoven with the still-mysterious estrangement of Thailand's Crown Prince Vajiralongkorn and his third wife, the former Princess Srirasm. Pongpat is Srirasm's uncle, and the couple's split was publicized soon after the police scandal emerged last year. But in a country where insulting the monarchy can bring a 15-year prison sentence, nobody is asking too many questions.

Police accuse Pongpat of leading a network responsible for offenses including money laundering, extortion and taking bribes from oil smugglers, illegal gambling dens and police officers seeking promotions. Pongpat was also convicted of insulting the monarchy because police said he claimed links to the monarchy to carry out the crimes.

"This is a very, very unusual case. There could not be another one like it," said police Col. Seehanat Prayoonrat, head of the Anti-Money Laundering Office, which is organizing the public auction.

The sale has been divided into two parts, each featuring 1,000 lots with items from the first auction valued at 50 million baht ($1.5 million). A second sale is scheduled for later this month.

Since Pongpat and several other police officials were arrested in November, authorities say they discovered assets worth more than 1 billion baht, or $30 million, including 104 plots of land and a massive art stash that was hidden in underground vaults and safe houses. Much of it is not up for auction, including 12th-century Buddhist statues that have been turned over to Thailand's Fine Arts Department, and ivory tusks, gold bars, luxury cars and diamond jewelry held by the anti-money-laundering agency.

"It's frightening. Surprising, how one person can do a thing like this," said Seehanat, saying that police typically find smaller stashes in corruption crackdowns. "Usually we find 10 cars. This time we found more than 20,000 pieces."

Pongpat had more time to accumulate wealth than many top-level Thai police officials, who typically rotate posts every two years. Pongpat held the top bureau job for several years, perhaps because of his family connections, according to police and other experts.

Still, analysts including Jomdet Trimek, a police officer turned academic, cast doubt on police claims that Pongpat's actions were unique.

"Was I surprised? I'm surprised there was eventually an arrest. A big general has never been arrested. But there was only an arrest because this was an order from up above that made it happen," said Jomdet, a professor of criminology at Bangkok's Rangsit University.

"Corruption is part of our police culture. This is a known fact. It is the norm and everyone takes part in it," said Jomdet. "Not everyone has the chance to be as corrupt as Pongpat. But the big bosses have a lot of money — that doesn't come from their salaries."

The junta that has ruled Thailand since toppling an elected government last May claims it is prioritizing the fight against corruption. Critics say the army's real goal is to cripple political allies of self-exiled former Prime Minister Thaksin Shinawatra, who was ousted in a 2006 coup, also on grounds of corruption and insulting the monarchy.

Senior police officials have started warning the lower ranks to clean up their act.

Last week in a chandeliered ballroom at the National Police Club, Thailand's chief of police, Somyot Pumpanmuang, led an anti-corruption seminar that focused on the well-known graft among lower-ranking officers. He dimmed the lights to show a video taken by hidden cameras of police extorting bribes from motorists and businesses.

"We cannot deny the existence of bribery and corruption," Somyot told his audience of 600 rank-and-file officers. Then he opened the floor to questions and asked for suggestions on how to end corruption. Nobody in the audience raised a hand.

"Please serve the people," Somyot told his officers. "And most importantly, obey the law."

He never mentioned Pongpat but referred to him on the sidelines as "a unique case" and "an extraordinary case." He laughed off a question about whether corruption persists at the top levels.

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Associated Press writer Thanyarat Doksone contributed to this report.