Police investigating the brutal assault of two teenaged boys that left one dead and the other seriously injured say the boys were beaten with a cord in their family’s New York church, but it's unclear why a church meeting turned so violent. 

New Hartford Police Chief Michael Inserra told reporters Friday that investigators have determined the boys had similar wounds and believe the beating caused the death of Lucas Leonard, 19. Lucas’ brother, Christopher, 17, remains hospitalized in serious condition since the alleged attack at the Word of Life Christian Church Sunday.  

The investigation suggests that “the extent of the bruising and contusions from the assault caused the death, but an official cause of death is still pending,” Inserra said.

The boys' parents, Bruce T. Leonard, 65, and Deborah Leonard, 59, who live in nearby Clayville, have been arrested and charged with first-degree manslaughter in Lucas' death. The two appeared shackled and in orange prison uniforms in a New Hartford courtroom for a preliminary hearing Friday.  

Church members have told police that a counseling session at the Word of Life Christian Church Sunday escalated into the fatal beating after a discussion of Lucas' desire to leave the upstate New York congregation.

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“It was emotional and spiritual abuse,” Chadwick Handville, a former member of the Word of Life Church told Fox News Friday about what happened in the church community when he was involved.

Four other church members, including the teenagers’ half sister, Sarah Ferguson, 33, were also arrested and appeared in court on felony assault charges. After a judge postponed their hearing Friday, two of the accused church members— David Morey, 26 and Linda Morey, 54—were released on bail and did not speak to reporters when leaving the courthouse.  

Prosecutors say they aren't prepared to go through with the hearing for David and Linda Morey because Christopher Leonard remains hospitalized and unable to testify. The Moreys' bail was set this week at $50,000 each. They are due back in court in court Dec. 15.

The judge granted an extension to prosecutors in the case of Ferguson and the fourth church member, Joseph Irwin. Assistant District Attorney Dawn Lupi says they need more time because Christopher Leonard remains hospitalized.

Lupi says there is a "strong possibility" the defendants will face more serious charges.The case was postponed until Oct. 23. All the suspects have pleaded not guilty.

Inserra said Friday that congregants explained that the counseling session was called Oct. 11 at the Word of Life Church, but police "still have not concluded why the session turned so violent."

Lucas was pronounced dead at a hospital Monday, after being found unresponsive and not breathing by other church members, Chief Inserra said. Hours later, Christopher was found on the second floor of the church, suffering from serious injuries,the New York Times reported.

“He wasn’t in hiding, but he wasn’t making himself available,” Inserra said. “And the family members were not telling us where he was.”

A defense lawyer for the boys’ mother says she felt helpless to stop the "intervention" that spiraled into a severe beating. An attorney for the son's father says what happened stemmed from a family matter and the parents didn't intend their sons' grave injuries.

 "We’re not alleging they intended to kill their son,” Scott D. McNamara, the Oneida County district attorney, told a news conference Wednesday. “We’re just alleging they were trying to seriously hurt their son, and ultimately he died from those injuries.”

The community surrounding the church had traded stories of odd behavior and awkward interactions with church members.

“Everybody in the whole town always said there’s something strange going on there; everybody felt that way,” Connie Toukatly, 76, a neighbor, told the Times. “But it’s so sad that it came to this point.”

The Associated Press contributed to this report.