I cannot tell you for sure what the lawyer is doing, and he certainly should be communicating with your brother. But I can tell you a couple of things which may help you to understand the proceedings:
An attorney can not enter a plea of guilty for his client unless the client authorizes him to do so, but he can enter a plea of not guilty on his behalf. This is because "not guilty" is the only plea that keeps all of a defendant's rights open, and while a criminal
case is pending, all criminal defendents remain in a "not guilty" posture. A not guilty plea is the only one that allows the lawyer to wait for discovery on the case and file for all hearings that your brother is entitled to and negotiate for a deal, if your brother wants one.
That doesn't mean that a formal pre-trial hearing was held or that the case is really going to trial on the scheduled date. It does mean that both sides have discussed the case with the judge in general terms so that the judge gets an idea of whether this is going to involve a disposition or whether the case may remain on his calendar for a long time while the charges are fought. Homicide cases do not get tried quickly. It's simply that every case in which there is no plea yet offered or contemplated is technically bound for trial.
There is an attorney/client privilege, and while concerned family members are always interested in what is going on with their loved ones case, a lawyer is required to keep much of what he knows confidential, and that means he can't share it with family either. Some lawyers don't like to have to explain that to family so they tend not to return their phone calls. But public defenders generally work for defender organizations, and they have supervisors.
If you want to hear what little your brother's lawyer is allowed to tell you about the case, call his office, ask to speak to the lawyer's supervisor, and complain about his leaving the family -- including his client -- completely in the dark as to what is going on with his case and that he won't return your phone calls.. Believe it or not, that's known to work. The supervisor will either tell you himself or make sure that the attorney will get back to you.
Hope this helps, but if it doesn't, or if you need clarification use the reply tab below to tell me what you don't understand and I'll be happy to add to my answer.