Kim Williams, 46, was booked on capital murder charges at about 3 a.m. Wednesday into Kaufman County Jail in Texas, about 40 miles east of Dallas. She was held on $10 million bond.
She reportedly confessed to involvement in the shootings. An affidavit says Kim Lene Williams "described in detail her role along with that of her husband" but was unclear on who she said committed the shooting.
A later report detailed the Wednesday affidavit that reveals Kim Williams told investigators a day earlier that husband Eric Williams was the triggerman in the slayings of Kaufman County District Attorney Mike McLelland and his wife Cynthia last month, and assistant prosecutor Mark Hasse.
Williams' arrest follows an intensive investigation into the slayings of the county officials. District Attorney McLelland, 63, and his wife, 65, were found shot dead in their Forney, Texas, home March 30. Assistant District Attorney Mark Hasse was gunned down in January outside the county courthouse.
Kim Williams' husband, Eric Williams, 46, was arrested on Saturday for making "terroristic threats" and was held in jail on $3 million bond.
Eric Williams was arrested on Saturday after authorities executed a search of his home and his storage facility from Friday afternoon into the early hours of Saturday morning. Police removed boxes, computers and guns from his residence. His bond was set at $3 million.
Authorities found 20 guns -- including assault rifles and handguns -- as well as a white Ford Crown Victoria inside a storage unit belonging to Mr. Williams that was similar to the one seen leaving the McLellands' neighborhood around the time of the killings, ABC affiliate WFAA-TV reported.
According to Eric Williams' arrest warrant, law enforcement officials received a threatening email sent by an anonymous source on March 31, that stated unless they "responded to the demands of the writer, another attack would occur."
The district attorney's office prosecuted and convicted Williams last year for two counts of felony theft, which resulted in his losing his justice of the peace position. According to the charging document, both the slain DAs carried guns because they "believed Eric Williams was a threat to their personal safety."
The officer who signed the affidavit, Kaufman County Sheriff's Sgt. Matt Woodall, said he had learned from other officers and county employees that Hasse and Mike McLelland both believed Williams blamed them for the loss of his job and carried handguns after the trial because they thought he was "a threat to their personal safety."
ABC News and The Associated Press contributed to this report.