A veteran Nassau County deputy is quitting over allegations that Sheriff Tommy Seagraves and his staff have bullied him for working as a self-described FBI informant in a probe of Seagraves and his agency.

Narcotics Detective Brandon Smith, in a letter sent to Seagraves Monday, said he could no longer work in a "hostile environment" that included being threatened for making secret recordings of Seagraves and his staff for the FBI.

Seagraves said there is no truth to Smith's claims of suffering from threats, harassment and retaliation. Seagraves described Smith, 31, as a "disgruntled employee" whose letter appeared to be a "press release" designed to damage Seagraves and his agency's reputation.

"Given all that has transpired in this case, that is not very surprising," Seagraves replied in a letter to Smith Wednesday.

FBI agents last year began seeking records of dealings between Yulee businesses, the sheriff and his agency. Agents also interview Seagraves and others in the Sheriff's Office. Questions have been raised about whether efforts were made to obstruct the probe.

A federal grand jury met several times, but no one has been charged. Seagraves has repeatedly denied any wrongdoing and said he doesn't know the status of the case. FBI Special-Agent-in-Charge Jim Casey has declined to comment.

Smith, a 10-year deputy who earns $42,000 annually, told Seagraves his last day would be Oct. 13. Smith remained on duty Thursday but referred all questions to Seagraves.

Seagraves stuck pretty much to his letter when the Times-Union asked him about the allegations. Seagraves wrote that if anyone has acted improperly, it's Smith.

"If it had been my intent to 'retaliate' against you or create a 'hostile environment,' you have provided more than ample justification to do so," Seagraves wrote. "That has not happened and will not happen."

He did not elaborate when asked what Smith did that would justify action against him. Seagraves said Smith is the only deputy who has made such claims against him.

"I'd have concerns if there was more than one person making that type of allegation," Seagraves told the Times-Union.

Smith wrote that Seagraves threatened him for making the secret recordings, "although you are aware that this was done as part of a federal investigation by the FBI in which I was acting as a confidential informant."

Smith did not give details of the recordings, when they were made or why.

Seagraves declined to comment on his knowledge of Smith's involvement in the investigation. Casey declined to comment on whether Smith ever helped the FBI.

Smith's letter also accuses Seagraves of failing to act on crimes committed by Sheriff's Office employees, but he gave no examples. Seagraves said all allegations of wrongdoing are investigated thoroughly.

Smith said that helping the FBI led to frivolous internal investigations against him, but he gave no specifics.

Records show Smith received remedial instruction in June for driving his police car outside Nassau for a secondary job and in May for arriving late for duty. He received a five-day suspension — halved from the original recommendation — in June for using an altered firearm against departmental policy.

Seagraves said Smith was never investigated for anything that didn't warrant attention.

Though Smith said he is retiring, Seagraves said Smith has neither met the age nor length of service requirements to retire and collect his state pension.

Seagraves said he accepted Smith's letter as his resignation.