Seven people who prosecutors say were involved in the beating death of a teenager during a counseling session at an upstate New York church were indicted on second-degree murder charges on Tuesday by a grand jury.

Lucas Leonard, 19, was beaten to death in October over 10 hours during a counseling session at the Word of Life Church in Chadwicks, New York, about 50 miles (80 km) east of Syracuse, prosecutors said.

His brother, Christopher, 17, received blunt force injuries when he was repeatedly struck during the same session, which was initiated because Lucas Leonard wanted to leave the congregation, prosecutors said.

The grand jury's indictment charged the brothers' father, Bruce Leonard, 65, with 13 criminal counts including second-degree murder, kidnapping and gang assault.

Charges of second-degree murder, kidnapping and gang assault were also brought against church pastor Tiffanie Irwin, 29; Traci Irwin, David Morey, 26, Linda Morey, 54, and Joseph Irwin, 26, who were all congregants at the church; and Sarah Ferguson, 33, the half-sister of Lucas and Christopher, the court document showed.

At least some of the Irwins are related to each other.

Tiffanie Irwin and Traci Irwin originally were not charged in the incident, while the other five were initially charged with first-degree manslaughter in Lucas Leonard's death.

An eighth person, church deacon Daniel Irwin, 24, was indicted on charges of second-degree manslaughter, kidnapping and gang assault.

The brothers' mother, Deborah Leonard, 59, was not named in the grand jury indictment but will appear in Oneida County Court on December 2 to face separate charges of first-degree assault against Lucas and second-degree assault in Christopher's beating, according to her lawyer Devin Garramone.

Deborah Leonard was initially charged with manslaughter, but Garramone said that charge was dropped.

Attorneys for the other people charged in the case could not be reached for comment.

Christopher Leonard, during a preliminary hearing last month, testified that he and his brother were beaten with an electric extension cord fashioned into a whip.

He said Tiffanie Irwin organised the counseling session.

Christopher said he attempted to resuscitate his brother before the boys were loaded into two separate vans. Lucas was transported to St Luke's hospital in Utica, New York, where he was pronounced dead, prosecutors said.

Most of those indicted in the case remain in jail on bail of tens of thousands of dollars each, while David and Linda Morey have been released on bail of $50,000 each, according to jail records.