Yes, in this usage, with an indirect object indicate must take "to". It would not take "to" if it was not directed to an individual. You CAN say: "He indicated the place" or "He indicated he was unhappy" or "He indicated that he would like dessert." "A red light indicates stop." But as soon as that action is directed AT an indirect object, it must take "TO"
"He indicated to me that he wanted dessert" "he indicated the place to me." "The pig indicated to the truffle hunter where the tasty fungi were located."