Two Dorchester men are behind bars on high bail today after their indictments for allegedly making threats relative to the shooting death of 16-year-old Jaivon Blake and the near-fatal shooting of a younger teen last year, Suffolk County District Attorney Daniel F. Conley said.

The Suffolk County Grand Jury last month indicted MATTHEW MITTON (D.O.B. 9/8/90) and MICHAEL TAVARES (D.O.B. 12/1/87) on multiple counts of witness intimidation, with Mitton facing four counts and Tavares facing three.

The pair were charged amid the same investigation that led to first-degree murder indictments against their alleged confederates, SHELDON MATTIS (D.O.B. 1/22/93) and NYASANI WATT (D.O.B. 10/5/93), said by prosecutors to be members of a street gang known as “Flatline.” Both are being held without bail.

Mitton was arraigned on Dec. 28 and held on $200,000 cash bail; Tavares was arraigned this afternoon and held on $15,000. A fifth man, RANDALL VARISTE-SCOTT (D.O.B. 11/8/93), was indicted for perjury for allegedly lying to the grand jury; he did not appear at his arraignment yesterday and a warrant has issued for his arrest.

Suffolk homicide prosecutors have said that people associated with the Flatline gang were on Levant Street on the afternoon of Sept. 25, 2011, when they saw the 14-year-old surviving victim standing outside a nearby convenience store.

Prosecutors say Mattis approached that boy to determine whether he was from a rival gang. After a brief discussion with the 14-year-old, Mattis allegedly went back to Levant Street and told his associates that the boy was a rival gang member. The younger boy, meanwhile, had met up with Blake and the two were walking away.

Watt allegedly armed himself with a .40 caliber semiautomatic handgun and met up with Mattis. Mattis allegedly helped Watt conceal the handgun by pulling Watt’s sweatshirt down over it. Prosecutors believe Watt then rode his bike toward the two boys and fired multiple shots, striking Blake in the back and the younger teen in the neck.

In the aftermath of the shootings, both Mitton and Tavares – who are friends and associates of the murder defendants – allegedly made threatening statements and gestures to individuals who had information on the case.

Attorney Edward Wayland represents Mitton and attorney Anthony Annino represents Tavares. Both will return to court on Jan. 10 for a motions hearing.