TAVERNIER, Fla. -

A man arrested earlier this week has been further charged after authorities say he made email threats to blow up sheriff's office substations and threats to kill or injure a detective.

On Wednesday, deputies said 21-year-old Cole Peacock of Tavernier was charged with falsely obtaining a credit card from Citibank, charging a large amount on the card and then paying Citibank with fraudulent checks.

As detectives were finalizing those arrest warrants Thursday afternoon, deputies said Peacock's defense attorney warned him he was going to be arrested.

Just before 6 p.m. Wednesday, deputies said Detective Sgt. Dave Carey, who was working on the case, began receiving emails. The emails appeared to be from other members of the Monroe County Sheriff's Office.

Out of the 78 such emails Carey received, deputies said four read, "DEATH DEATH DOOM DOOM YOU HAVE A BOMB AT ONE OF YOU SUBSTATIONS BETTER FIND IT SOON" (sic).

Deputies said ten of the emails said, "death death you will die."

During a past investigation of Peacock, deputies said in Feb. 2013, Peacock was charged with computer related crimes during which he showed Sheriff's detectives how he could "spoof" MCSO emails. "Spoofing" is creation of email messages with a forged sender address.

Carey suspected the emails were from Peacock. When he and Det. Robert Dosh showed up at Peacock's home on Azalea Street on Thursday evening, deputies said Peacock threatened the officers with what turned out to be an EpiPen, then stabbed himself in the neck with it.

Peacock struggled with officers who took him into custody on the outstanding warrants and on charges of resisting arrest and aggravated assault, deputies said.

Deputies said Peacock's computer was then seized, and his father was questioned about his son's activities that afternoon.

His father said Peacock had been pacing all afternoon, into and out of a room where his computer was set up. He said no one except himself, his son and his daughter were at home, said deputies.

Further investigation revealed the IP address, which created the threatening emails, belonged to a modem assigned to Peacock's house. Deputies said the modem was shown to have been active at the house at the time the emails were sent. The modem was in the same room as Peacock's computer, the room he'd been in and out of all afternoon.

Thorough searches were done at all MCSO buildings to ensure no bombs were hidden anywhere. Deputies said none were found.

Deputies said Peacock, who was already in jail, was charged with four counts making false reports of planting a bomb, explosive or weapon of mass destruction against state owned property, and four counts written threats to kill or do bodily injury.

The Federal Bureau of Investigation is also involved in investigating this case and may bring federal charges against Peacock in the future as well, said deputies.