Story highlights Christopher Leonard testifies he was beaten with a black cord

Officials say the beating caused his brother's death

Parents face manslaughter charges; four others are accused of second-degree assault

New Hartford, New York (CNN) Christopher Leonard spoke quietly, his head bowed, as he described the day his brother died.

One minute, they were standing in front of their church and facing questions from the pastor. Then, he said, the beating began.

"It was a black cord about 4 feet long," he testified in court on Wednesday. "It was folded twice."

The 17-year-old could be a key witness in a case that started in a small church in upstate New York and has drawn national attention. Police say Christopher Leonard and his brother Lucas were beaten in the sanctuary of Word of Life Christian Church in New Hartford, New York, after Lucas expressed a desire to leave the congregation

Lucas Leonard, 19, was later pronounced dead at a hospital. He suffered injuries so severe that emergency room doctors thought he had been shot, police said.

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