Yes, it would be in his best interest to get a lawyer. But it isn't in the interest of LE to have the suspect represented by an attorney during the questioning, especially since there is no indication that he is under arrest. If the suspect is arrested and invokes his right to counsel and his right to silence, then it would most certainly be in LE's interest to question him with an attorney present. Why? Well, they wouldn't be able to question him without his lawyer present. In fact, they couldn't even try to reinitiate conversation with him!
I suspect one among many of the reasons LE hasn't arrested him yet (let alone charged him) is that all sorts of constitutional rights vest when that happens. Right now, LE has maximum flexibility in terms of contacting the suspect and "offering deals."