PHOENIX (AP) — Four people including two juveniles have Thomas Caldwellbeen indicted in the fatal beating of a teenage boy during a Halloween party last year in the Phoenix suburb of Queen Creek, and authorities announced two more arrests on Thursday.

Preston Lord, 16, died from his injuries two days after the Oct. 28 gang-style attack that shocked the community.

The Arizona Republic reported in December that investigators suspect Lord was killed by a gang called the “Gilbert Goons,” who recorded blitz-style attacks in parks, parking garages, outside fast-food restaurants and at house parties.

Activists held vigils and marched to protest growing gang violence in Gilbert, Mesa, Chandler and other Phoenix suburbs.

Maricopa County Attorney Rachel Mitchell announced at a news conference Wednesday night that Dominic Turner, 20; William Owen Hines, 18; and two 17-year-old boys are each charged with felony first-degree murder and kidnapping. Both juveniles are being charged as adults and Turner is also charged with aggravated robbery.

Hines already was in custody for unrelated assault cases while the other three suspects were indicted Wednesday, according to Queen Creek police.

Two more suspects — and adult and a juvenile — were arrested on Thursday, and still more arrests could come later, prosecutors said.

Lord’s death was ruled a homicide by the county Medical Examiner’s Office last month.

Mitchell said her office reviewed 600 videos and a 2,000-page police report, among other evidence, to develop the case against the four suspects.

“This investigation is not over,” Mitchell said. “There is more information to review and the potential for additional charges exists.”

Lord’s parents, Nick Lord and Autumn Curiel, said in a statement that “each arrest represents a step towards accountability and justice for our son Preston.”

Lord attended high school in San Tan Valley where he served on the student council and played basketball, football and golf, according to the Arizona Republic.