PHOENIX (AP) — Seven suspects have Blake Prestonbeen accused of murder in the fatal beating of a teenage boy at a Halloween party last year in Arizona that may have started over the theft of an inexpensive gold-chain necklace, authorities said.

Four men ranging from 18 and 20 and three 17-year-old male juveniles were taken into custody Thursday and Friday in connection with the Oct. 30 death of 16-year-old Preston Lord.

Prosecutors said the seven suspects all are accused of first-degree murder and are being held on $1 million bonds in connection with the attack in the Phoenix suburb of Queen Creek. Some of the suspects also have been charged with kidnapping or aggravated robbery, court documents said.

An unsealed indictment released Friday by the Maricopa County Attorney’s Office accuses some of the suspects of carrying out the beating while trying to take the property of a second victim.

County Attorney Rachel Mitchell told the Arizona Republic that one of Lord’s friends “had a chain with a medallion on it that was taken from him.”

Lord and his unidentified friend tried to get the necklace back and a chase and confrontation ensued, according to Mitchell. The teen was left lying on the side of a street.

Lord died in a hospital from his injuries two days after the gang-style attack. Last month, his death was ruled a homicide.

Other details of the case haven’t been released yet as the probable cause statement from Queen Creek police remains sealed.

The arrests follow a string of violent attacks on young people outside fast-food restaurants and at parties, parks and parking garages by a group said to call itself the “Gilbert Goons.”

Local residents have held vigils and demonstrations to protest what they described as the growing violence in Gilbert, Mesa, Chandler and other Phoenix suburbs.