I found this article from early on in this case. It has details people might be interested in. I'll clip some here.
House #1 assault on Heinz by Synder, DaSilva and Valle:
"The arrests announced Thursday – of a 16-year-old and two 17-year-old boys – were connected to the Lazy Brook Road incident, according to police, during which the three suspects allegedly assaulted a 16-year-old boy.
“One juvenile assaulted the victim with a helmet (Valle)
,” Shelton Police Lt. Robert Kozlowsky said in a prepared statement.
After a short time the Shelton students left the party, but several of the participants then engaged in a group text with the two sides bad-mouthing each other. A witness told police the St. Joseph students knew the location of the Laurel Glen Drive party.
House #2
One witness told police that the
Honda Pilot made several passes past the party, and the occupants were throwing things from the vehicle and word spread that “those SJ kids are here,” according to the affidavit.
"Witnesses said the occupants exited the vehicle, and a witness told Bango several people said
Valle had been flashing a knife through the vehicle’s window, according to the warrant.
The witness said he approached the St. Joseph students and tried to calm the situation, and
Valle was holding what appeared to be a small pocket knife and was possibly trying to scare him."
A short time later, witnesses said one of
the uninvited teens (from house #1, St. Joes) struck or shoved someone and “a big fight” started, possibly involving as many as 25 teens.
The fight went to the ground, with witnesses describing a pile of people rolling around. But the situation appeared to calm down.
The group let Valle and his companion up and they began walking toward the Honda, and “everyone was leaving him (Valle) alone,” a witness said.
The witness said he watched as Valle suddenly turned and stabbed McGrath, who was standing nearby, according to the affidavit. Numerous witnesses at the scene also identified Valle as the person responsible, and picked him out of an 8-person photo lineup, Bango wrote."