Karate coach accused of sexual assault

A karate coach in Arlington was indicted Thursday on charges of sexually assaulting one of his students on several occasions, Middlesex District Attorney Gerard T. Leone’s office said yesterday. Thomas Donahue, 52, of Lexington, was charged with indecent assault and battery on a person under 14 and enticement of children, Leone’s office said in a statement. Prosecutors said Donahue asked the child, a 7-year-old, to help remove his leg brace in his office, where he then allegedly sexually assaulted the victim.