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Second Texas man charged with making 'terroristic threat' after DA's killing

Kaufman County Jail

Booking photo of Robert Allan Miller released by the Kaufman County Jail in Texas.

A second Texas man has been placed in Kaufman County jail on $1 million bond after being charged with making a terroristic threat against local officials reeling from the murders of two prosecutors.

Robert Allan Miller, 52, was booked on Thursday evening, according to Kaufman County jail records.

"A second person has been arrested and charged with making a terroristic threat following the Texas prosecutor murders," Lt. Justin Lewis with the Kaufman County sheriff's office said. "He is accused of making a threat against a county assistant prosecutor on Facebook."

The Texas county has been on high alert since District Attorney Mike McLelland, 63, and his wife Cynthia, 65, were found dead in their Forney home on March 30. Assistant District Attorney Mark Hasse was gunned down in a separate shooting two months earlier.

Multiple law enforcement agencies are investigating the slayings, including the FBI and Texas Rangers. No suspect or person of interest has been named in the killings.

Miller joins Nick Morale, 56, who was placed jail Tuesday and is also being held on $1 million bail on terroristic threat charges.

The two men have not been linked to the McLellands’ murders.

“Making threats against persons carried criminal penalties under state and federal law, with some of those penalties being pretty severe,” Lt. Justin Lewis of the Kaufman County Sheriff’s Office said at a press conference on Wednesday following Morale’s arrest. “All threats will be taken seriously.”

Texas Gov. Rick Perry announced Thursday that his office would add $100,000 to the reward being offered in the investigation of the McLellands’ death, raising the total reward to $200,000.

“We will leave no stone unturned,” Perry said at the news conference.

NBC News' Gabe Gutierrez contributed to this report.