The two Florida men reportedly met two months ago and spent time fishing and playing cards. On Friday night, one of the men, Luke R. Petruschke, was invited by the other, Manuel Vidal Vega, for a family dinner.

But the next morning, according to the police in Davie, Fla., Mr. Vega’s 3-year-old son told his father that Mr. Petruschke, 38, had groped him the night before.

An enraged Mr. Vega and a neighbor battered Mr. Petruschke so brutally with a concrete block, rocks, their fists and their feet that Mr. Petruschke had to be placed in a medically induced coma on Saturday, the police said. The official report described the beating as “savage.”

A police affidavit said that when Mr. Vega was about to be arrested, he told the police, “That is my son, what would you do?”