LARGO — The Pinellas County Sheriff's Office will not seek criminal charges against four former narcotics deputies forced out of their jobs last year amid allegations of trespassing, Sheriff Bob Gualtieri said Monday.

In a letter to State Attorney Bernie McCabe, Gualtieri said his office was right to get rid of the deputies, but did not have enough evidence to charge them.

Among other things, he said, officers were compelled to give statements as part of an employment disciplinary action and Florida law does not allow those statements to then be used to build a criminal case.

"While the evidence in the administrative case amply met the burden of proof to establish wrongdoing,'' Gualtieri said, "I have concluded that there is insufficient evidence to meet the burden of proof in a criminal case.''

Gualtieri sent thousands of pages of investigative documents to McCabe's office in case prosecutors want to pursue the matter further, the letter said. Armed trespassing is a felony.

The narcotics unit came under scrutiny in late 2011 after they raided the Seminole home of Allen Underwood and seized pot plants. Underwood had an outdoor surveillance system and said his cameras had caught Sgt. Chris Taylor and Deputy Paul Giovannoni trespassing several nights before the raid. Taylor jumped his fence, he said.

Narcotics officers seized the DVD images during the raid and Taylor ordered them destroyed.

The Tampa Bay Times also reported that Giovannoni had dressed in a Progress Energy uniform to gain access to another suspect's property.

Defense lawyers said detectives had secured search warrants by claiming they could smell marijuana from the street or adjoining property — but were trespassing to get close enough to the houses to peek inside, listen for fans or otherwise detect indoor pot farms.

During a deposition, one lawyer asked Deputy Kyle Alston under oath if he had ever seen his colleagues "jump fences,'' and Alston refused to answer.

After the Times reported this refusal, Alston admitted that he and deputy Michael Sciarrino had once broken down a fence to enter property illegally, Gualtieri said.

Taylor, Giovannoni and Sciarrino resigned in June. Alston was fired. None could be reached for comment.