Iskandar Puteri district police chief ACP Noor Hashim Mohamad said police also arrested the man’s 40-year-old wife and the son’s friend.
They are also looking for another friend of the boy.
He said the police, alerted by a member of the public, found the man’s body about 11am in the living room of a corner double-storey house with a stab wound on the left side of his chest.
A trail of blood led to the master bedroom on the first floor of the house, he said in a statement.
Hashim said there were signs of a struggle in the master bedroom where a clothes rack had toppled over and the bed was in disarray, but no items were missing and there was no sign of a break-in.
He said it was believed that the wife was jealous because the man, who was unemployed, apparently had a mistress.
The body has been sent to the Sultanah Aminah Hospital here, he added.