TAMPA —The city paid Eric Houston $85,654 a year to solve homicides for the Tampa Police Department.

But he may also have betrayed victims, divulging their identities for tax refund fraud, court records suggest.

About 4,600 individuals Houston checked out on state or national databases between 2010 and 2012 had fraudulent tax returns filed in their names, according to an affidavit obtained by the Tampa Bay Times.

And approximately 21 tax fraud victims had been involved in homicides or aggravated batteries investigated by Houston or his squad, the record notes.

GTE Federal Credit Union records cited in the affidavit show cash ATM deposits to an account shared by Houston and his wife for $18,000 in the spring of 2011.

The sum is a pittance compared with the typical take in tax fraud, but the details are the first public clues yet of what Tampa police Chief Jane Castor meant last month when she called Houston's alleged conduct "egregious."

The longtime homicide detective, 53, was fired April 24. Castor announced his termination that day at a news conference.

"It is clear that Houston's alleged criminal behavior is so egregious that it's necessary to take this step immediately," she said. "His actions do not represent the good men and women of this organization, and he does not deserve to wear the uniform of the Tampa Police Department."

Federal charges have not yet been filed. A federal grand jury investigation won't wrap up before Labor Day, according to a state court prosecutor.

The affidavit was filed Wednesday in U.S. District Court by Tampa police Detective Sharla Canfield, who serves on an IRS-Criminal Investigation task force and sought a warrant to search an external hard drive of Houston's.

Canfield wrote that there was probable cause to believe the drive contains evidence of conspiracy, identity theft, access device fraud and wire fraud.

Tampa police launched an internal affairs investigation of Houston in October after his wife, La Joyce Houston, was fired from her sergeant's position and arrested on charges of food stamp fraud and grand theft. The findings were turned over to the U.S. Attorney's Office in Tampa.

Police have remained tight-lipped in the face of the federal grand jury investigation of a veteran homicide detective whose work went into the prosecution of cop killer Dontae Morris, among others.

"It wouldn't be appropriate to comment on an ongoing federal investigation," police spokeswoman Laura McElroy said Friday. "The department took swift action and both of them were terminated."

Both Houstons factor into Canfield's affidavit, as does Tonia Bright, a police department civilian employee who recently retired from her post as a community service officer.

Central to the probe, however, is Rita Girven, the biological mother of a child the Houstons adopted and a woman with a history of theft and fraud arrests. According to court records, Girven assisted Tampa police as an informer.

In 2011, the mailbox at a Robles Park home once occupied by Girven had become a repository for prepaid debit cards that would be loaded with more than $27,000 in fraudulent refunds, Canfield learned.

At the time, Canfield and her colleagues were in the thick of discovering that Tampa had become the nation's tax refund fraud capital, an underworld that nationally was costing the Treasury more than $5 billion a year. The following March, Tampa police Detective Sal Augeri would tell Congress of a "crisis of epic proportion."

Canfield found cards in Girven's name. Refunds had been claimed using identities of dead people. And it was just the beginning of ties established between the police couple's close friend and tax fraud.

One link cited in the affidavit: A man died of a drug overdose on March 5, 2013. Eric Houston was a detective assigned to the case.

On March 6 and 7, the community service officer, Bright, ran the dead man's profile five times through DAVID, short for the state's Driver and Vehicle Information Database.

In a later search of Girven's Belmont Heights residence, authorities found a sticky note listing the man's name, date of birth and Social Security number. The handwriting could have been Bright's, the affidavit suggests, but further analysis was needed.

Bright, too, had spent a lot time onDAVID, "far more than what would be expected in the course of her normal duties," Canfield wrote. Bright searched state and national databases 13,000 times in a single year. In two years, about 120 of the identities she checked were used by someone to file fraudulent returns, the document states.

Bright and the Houstons all had a role in making Girven more comfortable in the Hillsborough County Jail, where she has been on a petit theft charge.

From August to mid October, La Joyce Houston spoke with Girven almost daily. Their frequent conversations about EBT cards led to the food stamp fraud charges against Sgt. Houston.

Girven wanted care packages. She wanted money in her commissary account. She wanted Detective Houston to get her an earlier court date.

On Sept. 7, she called him at home. She called him "Daddy." She wanted food. She wanted him to talk to a judge on her behalf. He said he would "see what stuff we can do."

On Sept. 24, agents searched the homes of Girven and her grandmother. Over the next three days, she made eight unanswered calls to the Houston residence, Canfield reported.

The day after Castor fired Eric Houston, investigators searched his police vehicle and found two envelopes. One, with Girven's return address at the jail, was addressed to "Mr. Mad" at the Houston's home address. The other, addressed to Girven but still sealed, said this: "I'm not mad at you. This thing just has to get finished so that nobody else has problems. Be safe."

Staff writer Sue Carlton contributed to this report. Patty Ryan can be reached at (813) 226-3382 or pryan@tampabay.com.