Eric Williams, Ex-court Justice to be charged with murders of Texas district attorney, his wife and assistant DA

A former justice of the peace is reportedly set to be charged with three murders, including a former Texas district attorney and assistant DA, after he was arrested on Saturday.

Eric Williams, 46, has been arrested by authorities investigating the murders of District Attorney Mike McLelland and his wife, Cynthia, last month - and the fatal shooting of ADA Mark Hasse in late January.

Williams was booked into Kaufman County Jail early Saturday morning for making terroristic threats and 'insufficient bond.' He is being held on a $3million bond.

Sources tell CBS11 that he will be charged with capital murder in the deaths of Mr and Mrs McLelland and the assistant attorney.

Williams had previously been successfully prosecuted by the murdered officials.

Police reportedly zeroed in on Williams after several emails making threats to other county officials were linked to him.

A police source told The Dallas Morning News: 'We can sleep a lot better tonight.'

Williams' wife, Kim, told the paper: 'I'm really tired. I was up almost all night. I'm not ready to talk.'

A neighbor told the Dallas Morning News that he knew Williams to be a 'nice guy' who was known in the neighborhood for riding around town in his Segway.

Williams was convicted in March 2012 by the district attorney's office of burglary of a building and theft by a public servant, the station reported.

Surveillance cameras caught Williams taking computer equipment from a county building. As part of his appeal, Williams claimed McClelland and Hasse didn't like him.

He was sentenced to two months of probation and lost his justice of the peace position as a result of the conviction.

Federal and local authorities searched Williams' home Friday as part of an investigation into the McLellands' deaths.

Williams' attorney, David Sergi, released a statement at the time, saying his client 'has cooperated with law enforcement and vigorously denies any and all allegations.'

'He wishes simply to get on with his life and hopes that the perpetrators are brought to justice,' Sergi said.

Earlier this month, Williams said he voluntarily submitted to a gun residue test and turned over his cellphone after authorities contacted him while investigating the deaths of the McLellands.

Authorities have released little information about the case except to say they continue to follow leads, including possible ties to a white supremacist gang.

One month before Hasse's death, the Texas Department of Public Safety issued a warning to authorities statewide that the Aryan Brotherhood of Texas could retaliate for an October indictment that targeted some of its leaders.

McLelland's office was involved in that investigation.

Earlier this month, a speaker had drawn applause from mourners at the McLelland's funeral, when he said of their killers: 'Chase 'em down. Go get 'em. Bring 'em to justice... Take them out of the hole they come from.'

Chris Heisler made the remarks as he led an emotional memorial service on April 4 for the couple who had been murdered at their Texas home near Forney on March 31.

Loved ones remembered the couple's love, warmth and public service. Dozens of law enforcement officers and public officials, including Texas Governor Rick Perry, were among the hundreds who attended the service.

Friends reportedly found the bodies of the DA and his wife after going to their home on March 31, having not heard from them in almost 24 hours. They were found with multiple gunshot wounds.

At their funeral service on April 4, Mr and Mrs McLelland shared a single, flag-draped casket inside the suburban church.

Mrs McLelland had been cremated and an urn with her remains was placed inside her husband's coffin.

McLelland had addressed many of the same people two months earlier, after the slaying of Mark Hasse, one of his prosecutors. Hasse was gunned down near the Kaufman County courthouse while going to work.

The deaths were feared to be planned attacks by violent white supremacist gang, the Aryan Brotherhood of Texas.

McLelland in particular was pivotal in the prosecution of a senior member of the Aryan Brotherhood of Texas last year who received two life terms following a shoot out.

In the months after Hasse was killed, McLelland began to carry a gun everywhere and took extra caution when answering his door.

He told The Associated Press in an interview shortly before his death that he was warning his employees that they needed to be more cautious as well.

'The people in my line of work are going to have to get better at it,' he said of dealing with the danger, 'because they're going to need it more in the future'.