The FBI arrested a St. Petersburg homicide detective Wednesday on public corruption charges, accusing him of using his position to extort cash, shoes and a flat-screen television from a confidential informant.

Detective Anthony Foster demanded the gifts in exchange for helping the informant get lighter sentences on theft and drug charges, according to a criminal complaint. Foster, a 13-year department veteran and hostage negotiator, is charged with wire fraud and interference with commerce by threats. If convicted, he could face 20 years for each charge.

Foster, 39, was arrested at noon Wednesday when he went to the State Attorney's Office complex on 49th Street N in Largo for a work-related matter. He didn't know that authorities planned to take him into custody but was arrested without incident, said FBI spokesman Dave Couvertier.

His arrest shocked the St. Petersburg Police Department and City Hall. Police Chief Chuck Harmon and Mayor Bill Foster said they knew nothing of the investigation until the arrest.

"It is certainly devastating when allegations are brought forward that one of your officers has committed a criminal act, and the fact that he may have used his position in the course of that act even makes it worse," Harmon said in a statement.

Anthony Foster's arrest also could have far reaching implications for dozens of criminal cases the detective worked on.

The Police Department will conduct an internal investigation into Foster's conduct regardless of whether he's convicted of the charges, Harmon said, noting there is no information to suggest anyone else in the department was involved or aware of Foster's conduct.

At a first appearance before U.S. Magistrate Judge Anthony Porcelli in Tampa on Wednesday, Foster was ordered to have no contact with three witnesses in the case or the informant. He and his wife signed a $25,000 unsecured bond.

He wouldn't respond to questions from reporters as he left the courthouse, flanked by his wife and federal public defender Alex Hall.

"We really don't have any comment," said Hall, who was assigned to represent Foster until he hires his own attorney. "We're just going to wait and see what happens in court."

FBI agents on Wednesday searched Foster's home in Pinellas Point, a quiet neighborhood at the city's southern end. Agents carried bulging brown paper bags from the home. One agent carried a laptop bag.

Foster, who makes $65,894 a year, was put on immediate unpaid leave. If convicted, he could lose his pension.

Mayor Foster, no relation to the detective, said Harmon told him of the arrest at 12:30 p.m.

"(Harmon and I) are just following the federal case, and it's both of our prayers that this won't reflect negatively on the 535 other sworn officers who put their lives on the line every day," the mayor said.

The 14-page criminal complaint depicts the development of an increasingly unequal partnership, where Anthony Foster extracted more and more from an anxious source afraid of jail time.

The informant started working with Foster on criminal cases in 2008, the complaint states. The next year, Foster started making demands in exchange for his help in getting lighter sentences.

According to the complaint: Foster accepted cash and property worth more than $8,000 from the informant. He demanded $7,500 for a Suzuki M109 motorcycle and took a 40-inch Samsung television, six pairs of Nike Air Jordan basketball shoes and groceries bought with the informant's EBT card.

Meanwhile, Foster testified about how the informant was assisting him in criminal investigations. The informant told the FBI that Foster's intervention resulted in reduced sentences, which was confirmed by Jason Shearn, the agent investigating the case, the complaint states.

Early in the relationship, Foster had demanded a plasma television from the informant, who couldn't afford one then, the complaint states. But by this April, the informant offered to give him one and cash for the motorcycle.

What the informant didn't say was there would be an audience.

On April 15 at a Publix parking lot on 54th Avenue S, the FBI snapped photos and recorded audio as Foster, who was on duty, said: "I thought you were bringing my damn money."

Foster took $325 from the informant and then walked to the rear of the car and pulled out a boxed Samsung television. He placed it in the trunk of his St. Petersburg police cruiser, the complaint states.

This exchange was related to the informant's arrest on a grand theft charge in Hernando County in February 2010, the complaint states. Foster had promised to put in a good word with the Hernando County state attorney.

"The informant feared a term of imprisonment and perceived the only way around such a term would be to provide Foster with the property he demanded," the complaint states.

Authorities notified officials in the 5th Judicial Circuit to the threat of Foster presenting perjured testimony in a Hernando County courtroom.

"They were not going to sit back and let us get sucked into that," said Ric Ridgway, chief assistant state attorney of the 5th Judicial Circuit.

He said Foster never testified in the case.

"It didn't come to that point," Ridgway said.

Foster did call the state attorney's office to vouch for the informant. He also had his supervisor call. The unnamed sergeant faxed a list of four major criminal cases in which he said the informant had provided assistance, including a March 23 murder.

However, in an interview with the FBI, the informant denied providing information on any of those cases.

When asked about the sergeant's role in the case and whether he was a target of a wider probe, the FBI said they expect no additional arrests.

"Our investigators believe the supervisor was duped by Foster," Harmon said. "They had no reason not to believe him."

Foster was hired by the department in 1997, his career marked by highs and lows.

He was lauded in performance reviews for closing robbery and homicide cases. On Jan. 24, he was one of the hostage negotiators who spoke by phone to fugitive Hydra Lacy Jr. during the shoot-out that cost two officers their lives.

His personal life, however, got in the way of his climb up the ranks. He often found himself in trouble with women and alcohol.

He was suspended four times, in 1997, 2004 and twice in 2005.

Three of the suspensions came after Foster had fights or arguments with women that required the police to intervene. Two of those incidents involved alcohol. Meanwhile, his relationships with two women led to two paternity suits, in 1998 and 2003, that resulted in him owing hundreds of dollars a month in child support.