NASHUA – A third man charged in connection to the killing of a Mont Vernon mother in October will plead guilty later this month.

William Marks, 18, of Amherst, filed an intent to plead guilty at Hillsborough County Superior Court last week. The state attorney general’s office will recommend a sentence of 30-60 years in prison, according to documents filed at the court.

Marks is one of five men charged in connection to the murder of Kimberly Cates and the attack on her 11-year-old daughter, Jaimie, on Oct. 4 in Mont Vernon.

Last month, Marks dropped his defense attorneys in favor of a Massachusetts lawyer, according to court documents.

Two men, Steven Spader, 18, and Christopher Gribble, 20, both of Brookline, are facing first-degree murder charges.

Two other men, Quinn Glover, 18, of Amherst, and Autumn Savoy, of Hollis, have already pleaded guilty and agreed to testify for the state, according to court documents.

Spader and Gribble are accused of entering the Cates’ Trow Road home with the intention of robbing it and killing anyone inside. Authorities say they used a machete and a knife to kill Kimberly Cates and seriously injure Jaimie Cates.

Glover and Marks were in the home and also armed at the time of the alleged attack. Savoy has pleaded guilty to helping the others attempt to cover up the murder after the fact.

Marks will appear at superior court Aug. 16 to enter guilty pleas to conspiracy to commit murder, accomplice to first-degree assault and conspiracy to commit burglary. The state will drop a charge of accomplice to first-degree murder, according to court documents.

The state will recommend prison sentences of 15-30 years for the conspiracy to murder charge, and 7½-15 years, served consecutively with the murder charge, for the accomplice charge. It will recommend another 7½-15 years for the conspiracy to burglary charge, to be served consecutively with the assault and murder charges, according to court documents.

In all, Marks could be in prison until he’s nearly 80 years old.

The court documents do not detail to what extent Marks would be required to cooperate with state prosecutors.

Assistant Attorney General Peter Hinckley declined to comment. Marks’ new defense attorney, Peter Leahy, was not available for comment.

Glover and Savoy both agreed to testify for the state in exchange for their sentences.

The attorney general’s office has recommend 20-40 years in prison for Glover and five-12 years in prison for Savoy, according to court documents.

Gribble, one of the men accused in the actual attack on Kimberly and Jaimie Cates, has filed his intention to use an insanity defense. He will next appear in court Aug. 23, when his attorneys will inform a judge whether they will pursue an insanity plea for him.

Two days later, Spader’s attorneys will be in court to argue for their motion to suppress evidence. They contend that police were too suggestive when showing two witnesses photos of Spader and Marks and didn’t use photo lineups.

Spader’s attorneys, Jonathan Cohen and Andrew Winters, have also filed a motion to move the trial to an area where there has been less press coverage of the case.

Joseph G. Cote can be reached at 594-6415 or jcote@nashuatelegraph.com.