Yakima County prosecutors on Friday dismissed charges against the sole remaining murder suspect in the Goggin family triple murders.

Tracy Culton, 36, had been charged with first-degree murder as a principal or as an accessory in the February 2011 bludgeoning deaths of Bill and Pauline Goggin and Bill’s 98-year-old mother, Bettye.

But prosecutors said a renewed investigation that followed the shocking collapse of the murder case against fellow defendant Kevin Harper found insufficient evidence to proceed against Culton.

Yakima County Superior Court Judge Ruth Reukauf dismissed the charges without prejudice, meaning they could be refiled.

“It doesn’t sound like that’s going to be the case, but you need to be aware the option remains open,” Reukauf told Culton, adding, “Any questions?”

“No, your honor,” Culton quietly replied.

In response to inquiries by Reukauf, Chief Criminal Deputy Prosecutor Ken Ramm said he had spoken to relatives of the Goggin family and that they “understood” the decision to dismiss the case.

Afterwards, Ramm declined comment, deferring instead to a news release issued by the prosecutor’s office. Culton’s lawyer, Barry Woodard, was with his client and did not return a call seeking comment.

Mike Morrisette, a friend of Bill and Pauline Goggin, said he remains frustrated with the lack of progress in the case, generally considered to be Yakima County’s most notorious homicide since the late 1980s, when an elderly Parker couple and an Outlook family of four were brutally slain in unrelated cases.

“Somebody swung that bat or hammer or whatever it was,” said Morrisette, a former head of the Greater Yakima Chamber of Commerce. “I don’t know where we go from here.”

Lawyers in the case have said Culton boasted to at least eight people that she — but not Harper — participated in the slayings, which investigators believe were committed in the course of a burglary. Bill Goggin, 61, co-owned a civil engineering firm in Yakima, and he and his wife were described by friends as a fun, happy couple who were active in vintage car clubs.

But sheriff’s detectives had doubts about Culton’s guilt from the beginning and believed she was mentally disturbed. Betraying a disconnect with the prosecution, they failed to submit her DNA for testing.

According to the news release, prosecutors said a new set of veteran detectives took over the investigation following the collapse of the Harper case, and determined Culton was not involved in the “planning or participation” of the slayings.

They said dozens of witnesses were interviewed and supported Culton’s unspecified alibi. They said she also passed a lie-detector test.

Moreover, prosecutors said in their news release: “Within the last week, the state has also received results from the Washington State Crime Lab regarding forensic evidence related to the crime. None of the results implicates Ms. Culton.”

In a follow-up call, Yakima County Prosecutor Jim Hagarty declined to discuss the new forensic results. Court records show that at least some of the forensic evidence involved DNA testing.

“I have no comments on the results, other than it does not implicate Ms. Culton,” Hagarty said, repeating the language of the news release.

With the dismissal of case against Culton, the only remaining defendant is now Tennance Buckingham, 50, who is charged with trafficking in stolen property from the Goggin home and first-degree criminal assistance.

His next court date is hearing set for March 28, with a trial date of April 8.

Harper was once considered the prime suspect, but prosecutors cut a deal with him after a series of missteps that included the late emergence of a surprise potential alibi witness.

Harper agreed to a seven-year sentence for his plea to two charges related to the theft of a .22-caliber pistol stolen from the Goggin home. A sentencing date has not be set.

Prosecutors also agreed to dismiss an accessory charge against his wife.

Hagarty said the investigation remains active.

• Chris Bristol can be reached at 509-577-7748 or cbristol@yakimaherald.com. Follow him on Twitter at twitter.com/ChrisJBristol.