New London — Court documents regarding 30-year-old city resident James Armstrong, arraigned in New London Superior Court Monday morning, paint the picture of a man whose mental state was deteriorating in the years before he allegedly shot and killed his cousin in April.

Armstrong is accused of fatally shooting 31-year-old Ralph Sebastian Sidberry in North Stonington on April 12. Court officials on Monday lowered his bond from $2 million to $1.5 million, citing his lack of a criminal record, early cooperation with police and possible mental health issues.

According to an arrest warrant affidavit, state police first were called to 628C Lantern Hill Road at 4:16 p.m. That wasn’t when shooting happened, though. According to the affidavit, Sebastian Sidberry went outside to do yard work after 3 p.m. that day while his wife, Rebecca, stayed inside with their infant. Rebecca told police she heard a car pull into the driveway and Sebastian Sidberry told her through a side door that “cousin James is here.”

Rebecca told police she found it odd that someone had visited unannounced because that rarely happened. But when she heard the gunshot, the affidavit states, she didn’t think much of it because she hears them often where she lives.

It was several minutes later that she went outside, wondering where Sebastian Sidberry was, and found him hunched over and bleeding from the head, according to the affidavit.

Without a phone of her own, Rebecca drove to her neighbor’s house to call 911.

Police quickly learned a man known only as “cousin James” might have been at the scene. They drove to 12 Acorn Court, Armstrong’s last known address, in an attempt to find him.

According to the affidavit, troopers promptly located Armstrong at the Acorn Court home where he lived with  relatives. Armstrong allegedly told police he had gone to Sebastian Sidberry’s residence to say, “What’s up?” He said the two were close in their youth and still were in April. He denied having shot Sebastian Sidberry.

A witness later told police that Armstrong got to 12 Acorn Court at 4:32 p.m. Police noted in the affidavit that that would put him at Sebastian Sidberry’s residence at 4:06 p.m., assuming he drove straight home.

Police said Armstrong consented to having a gunshot residue test done on his hands. He additionally told police he owned a firearm, a .40-caliber Kahr Arms pistol he purchased in January. According to the affidavit, Armstrong told police it never had been fired.

When examining the firearm the following day, troopers found one round missing from the gun’s six-round magazine, the affidavit states. They additionally found another loaded six-round magazine and a 50-round box of ammunition containing 38 rounds.

Later forensic testing determined the single bullet that killed Sebastian Sidberry “could have been fired” from the Kahr Arms pistol, but “due to damage and lack of detail, a more conclusive determination could not be rendered.” Testing also determined particles of lead were present on Armstrong’s hands on April 12, the affidavit states.

According to police, Armstrong on April 24 came to Troop E in Montville to inquire about the return of his vehicle, which police had seized. Police said he agreed to speak to detectives about the incident a second time.

This time, the affidavit states, Armstrong told police Sebastian Sidberry was a bad person who was spreading HIV through the Eastern Pequot Tribe. Analyses showed Sebastian Sidberry had neither HIV nor AIDS. According to the affidavit, “Armstrong refused to believe the results.”

In the affidavit, witnesses described Armstrong as a loner who had trouble making friends and fitting in with the tribe. One said he often sent emails about the spread of HIV through the tribe. Another said he had been "decompensating mentally over the past three years." That witness told police Armstrong was upset Sebastian Sidberry got to live in the home at 628 Lantern Hill Road, which is part of the tribal reservation, and he didn’t. The disagreement, the witness said, was “common knowledge among the tribe.”

The same witness told police that Armstrong, after a summer 2016 dispute with Sebastian Sidberry, said he could “put two in (Sebastian Sidberry's) head.” The witness said he and others present believed Armstrong was joking, according to the affidavit.

Based on those things and more, police in July obtained a warrant for Armstrong’s arrest. They learned from a relative that he had moved to Missouri and alerted police there.

Armstrong was arrested July 27 in Missouri and held in a jail there until he was brought back to Connecticut this past weekend.

Sebastian Sidberry, who was the permittee of the Globe Spirit Shop in New London, also was known as Sequoyah Tall Tree. In an August statement, his mother, Eastern Pequot Tribal Chairwoman Katherine Sebastian Dring, called for Armstrong to "be prosecuted and sentenced to the maximum punishment under the law."

Armstrong’s next court date is slated for Oct. 3.

l.boyle@theday.com