A jury in Wichita Falls on Wednesday convicted Benjamin Prince of capital murder in the violent domestic dispute. Prosecutors did not seek the death penalty, so Prince received an automatic life prison term.
The victim was 23-month-old Trebian Prince.
Investigators say Prince is also accused of wounding the boy's mother, Nicole Grant, and fatally shooting his cousin, John Prince Jr.
Grant testified the argument was over Benjamin Prince's involvement with another woman.