Kevin Harper was a prime suspect in the February 2011 slayings of Bill Goggin, owner of a Yakima engineering firm; his wife, Pauline; and his 98-year-old mother, Bettye.
Last fall, prosecutors dropped the murder charges and Harper pleaded guilty to lesser theft and firearm offenses. They said then that they did not believe they could prove murder charges against Harper.
The decision, which stunned the victims' relatives, followed the appointment of a special prosecutor to investigate whether authorities improperly eavesdropped on jail calls between Harper and his attorneys.
The Yakima Herald-Republic reports that during a hearing Friday, prosecutors accused Harper of somehow violating a confidential cooperation agreement. They wouldn't give any further details, however, and said they'd explain it to the judge in a hearing closed to the public.
Chief Criminal Deputy Prosecutor Ken Ramm told Superior Court Judge Ruth Reukauf he wanted to avoid tainting the jury pool and prompting an expensive change of venue.
The judge expressed reluctance to close the courtroom, and ordered a June 13 hearing to allow news organizations and others to object. There is a strong presumption of openness in criminal cases, and appeals courts generally frown on closing them.
Defense attorney Pete Mazzone strongly objected to undoing the plea deal. He accused prosecutors of cutting the deal in bad faith at a time when the case was falling apart.
The plea deal was used to buy time for detectives to further investigate Harper, said Mazzone. He said prosecutors turned over 1,800 pages of new evidence Thursday.
Mazzone complained that sheriff's detectives got help on their second round of investigating Harper from the Yakima Police Department, Seattle police, the State Patrol and the attorney general's office. He did not elaborate on their findings.
"It's a whole new investigation, is my understanding of it," he said.
The victims were found bludgeoned to death in their home in a gated community west of Yakima during what may have been a burglary.
Harper, 30, has not been sentenced. Prosecutors agreed to recommend just over seven years.
As part of the plea deal, prosecutors dismissed accessory charges against Harper's wife, Crystal Gray-West.
Prosecutors dropped charges against another defendant, Tracy Culton, earlier this year. They said it had become clear she wasn't involved.