El Paso County Judge Jonathan L. Walker took a leave of absence earlier in August after three criminal sources, including two jail informants, warned that leaders of 211 Crew, a white supremacist prison gang, planned to kill him, sources told The Denver Post.
He was to return to the courtroom Monday, the Post reported Sunday.
One source, who has direct access to and knowledge of sealed court documents, verified details of the investigation, including allegations that Clements' assassination was ordered by leaders of the white supremacist prison gang, the Post said.
Police said parolee Evan Ebel killed Clements and pizza delivery driver Nathan Leon in March before he was killed in a shootout with deputies in Texas.
The source said investigators searching Ebel's belongings after his death found a list identifying Clements and other officials -- including Gov. John Hickenlooper -- as possible targets, the Post said.
Former Corrections Department parole chief Tim Hand said 211 Crew members had targeted him in an assassination plot, correspondence between gang members intercepted by investigators indicated.
Walker has signed about 20 search warrants against members of 211 Crew, allowing investigators to search gang leaders' homes and cellphone records for evidence that could potentially link them to the Clements slaying conspiracy, a source told the Post.
The source said Walker also took security precautions, including buying a .380-caliber handgun, moving from his house and wearing body armor.
During the two weeks of leave, the source said, Walker went into hiding after Colorado Springs SWAT team members told him he was a "sitting duck" at his home.