WOBURN, Mass. (AP) — A 23-year-old Lowell man is held without bail after pleading not guilty to second-degree murder in the shaking death of his infant son.

Christopher Berry was arraigned Monday at Middlesex Superior Court in the death last May of his 9-week-old son William.

Prosecutors said Lowell police who responded to Berry's home May 11 found the baby with blood coming from his mouth, and with breathing difficulty. Berry first said he found the baby unresponsive when he tried to wake him. Prosecutors said he later told police he briefly shook the boy out of frustration with his crying.

William's injuries included swelling and bleeding of the brain. He died May 15.

Suffolk County prosecutors are handling the case because a social worker who may be called to testify is a relative of the Middlesex County district attorney.