A 23-year-old man beat an 18-month-old boy to death after the little one urinated on him during a diaper change, according to authorities.

Martin Alvarado Jr., who was watching his girlfriend's child in the Cicero home they shared, appeared in court Monday on a first-degree murder charge and was denied bail. Alvarado confessed on video to police over the weekend, according to a press release from the town of Cicero.

The baby, Edwin Eli O'Reilly, died at MacNeal Hospital in Berywn on Thursday at 6:38 p.m. He suffered from multiple blunt force injuries, according to the Cook County medical examiner. Alvarado flew into a rage while changing Edwin's diaper after he was doused with urine, according to Cicero police, and he repeatedly struck the child.