Kemarni Watson Darby suffered more than 20 rib fractures, some caused by a “shod foot”, with force “akin to a road traffic accident”, Birmingham Crown Court heard. Convicted drug dealer Nathaniel Pope, 32, had denied murder, blaming Kemarni’s mother, Alicia Watson, 30, for the boy’s death at their flat in West Bromwich, West Midlands, in June 2018.
Watson was cleared of murder but convicted of causing or allowing Kemarni’s death.
The court heard Pope had inflicted the fatal blow while Watson left the tot with him for 40 minutes. Post-mortem tests revealed extensive injuries to Kemarni’s ribcage, indicating four or more separate attacks in previous weeks.
His body had 34 external injuries in all, including bruising from “repeated and, in all probability, sustained assaults”.
Kemarni’s father, Darren Darby, told the jury he knew his son was being hit by his “strict” mother, adding: “We all let him down.”
Pope, from Wolverhampton, and Watson, of Handsworth, Birmingham, will be sentenced later.
The court heard they continued to live together for months after the boy’s death.
A serious case review will be published shortly.
Det Supt Shaun Edwards said: “I can only begin to imagine what the final few weeks of his [Kemarni’s] life will have been like.”