Philip Chism was "calm and measured" as he told investigators what he wanted them to know about the death of Danvers High School teacher Colleen Ritzer of Andover.
"Very bad things happened," Chism told the officers, Danvers police Sgt. Phil Tansey and state police Lt. Norman Zuk.
But first, he had ordered his mother, Diana Chism, out of the interrogation room at the Danvers police station, where he'd been brought in the early morning hours of Oct. 23, 2013.
"I'm here because I love you," she told her son, but he responded, "I don't care."
"I have a very strong dislike for (my mother) and anybody else," he told officers after she left.
Chism would go on, in a way prosecutors have described as "minimizing," to describe the death of Ritzer, 24, of Andover. At times, he corrected them as they pressed for details that in a number of instances were at odds with the evidence, including his claim that he did not sexually assault his teacher.
And he claimed that Ritzer provoked the attack with an insult or "trigger" word, which he then refused to disclose.
But while Chism was "cooperative" with police, a Salem Superior Court judge found on Tuesday that he did not fully understand his constitutional rights before deciding to speak to the investigators.
In a lengthy decision released Tuesday afternoon, Judge David Lowy barred prosecutors from using that confession by Chism, now 16, when he stands trial later this year — unless he takes the stand in his own defense. If that happens, prosecutors could use the statement to challenge his credibility during cross-examination.
"The court is not convinced, based on the totality of the circumstances, that the defendant waived Miranda beyond a reasonable doubt," Lowy wrote in the 48-page ruling.
He also ordered that Ritzer's cellphones, which were found as a result of information given by the teen during questioning, be suppressed.
Some statements admissible
Prosecutors will be allowed to use statements Chism made to Topsfield police, however, including an admission that the blood on a box cutter was "the girl's," and can use as evidence the items he was carrying, including Ritzer's wallet and underwear. The judge found that evidence admissible under a theory that Topsfield police found them while in the role of "community caretakers" who had just found the missing teen.
Topsfield police had found Chism walking alone on Route 1 and stopped to talk to the teen, later bringing him to the police station.
"The defendant and his belongings were legitimately detained by Topsfield police during their community caretaking inquiry," Lowy wrote. He noted that "one could not imagine a situation more suited to an officer's role as a community caretaker than searching for and discovering a missing juvenile."
The decision reveals some details of what Chism said inside a Danvers police station interrogation room, details that have not been previously disclosed. That's due to a request by the defense that the interrogation video and a transcript, which Lowy relied on extensively in making his findings, be sealed from the public. The defense contends that the "inflammatory" nature of Chism's statements will taint the pool of potential jurors.
Lowy denied the request earlier this year and was upheld by an Appeals Court judge, but the defense has further appealed to the Supreme Judicial Court to keep the materials under lock and key until Chism's trial. Lawyers for The Townsman's sister papers, The Salem News and The Eagle-Tribune, as well as The Boston Globe are challenging the impoundment request.
However, Lowy referred repeatedly to the teen's demeanor and answers on the video in his ruling Tuesday.
While Chism was "introspective, polite, calm and cooperative," Lowy found, he could not conclude that Chism fully understood his right not to speak to police that night.
"The defendant twice indicated a disinterest in speaking to the Danvers police," Lowy wrote in the decision. "During the recitation of Miranda, the defendant did not appear to be fully engaged as the officers explained his ... rights to him."
Lowy also concluded in the decision that Chism's mother, Diana, was never explicitly told by investigators that her role was to assist her son in understanding his rights and whether he should waive them.
Prosecutors could still seek to use the statement against Chism in rebuttal if he decides to testify in his trial, currently set for Oct. 7, the judge ruled.
Either side could seek to appeal the ruling prior to trial, though such appeals are rarely granted.
"We are reviewing the decision," said Carrie Kimball Monahan, a spokeswoman for the Essex District Attorney.