RIVERHEAD, N.Y. (AP) – A man faces 20 years in prison after pleading guilty to manslaughter in the death of his 4-month-old son last year from “shaken baby syndrome.”

Joseph Perri, 25, of North Lindenhurst, admitted his role in the death Friday before Suffolk County Judge C. Randall Hinrichs, who – under a plea agreement – will impose a 20-year term at the April 19 sentencing. Perri had faced up to 25 years in prison.

His infant son, Gabriel, died March 2, 2006, at Good Samaritan Hospital from what doctors called injuries consistent with being shaken. Police were called to the Perri home after a report that the 4-month-old was having difficulty breathing; the child died three days later.

The fatal injuries occurred just four days after Perri was arrested for assault and endangering the welfare of a child after intentionally dropping his son, causing head injuries, authorities said.