Your reply changes the picture, because I was in the process of telling you to go talk to the public defender's office and that in an emergency situation they can be prevailed upon to go to bat for an indigent defendant before they are formally appointed by a judge.
It would appear that there has been a bail determination made. It's high because the charges are violent and very serious, but he was entitled to have bail set, and it's been done. Who set bail on him? Did he appear before a magistrate?
Most defendants do not/should not testify before the grand jury, and you've been informed correctly that a defense attorney cannot participate in grand jury proceedings. The grand jury is a secret proceeding controlled by the DA. They do not decide guilt or innocence. They hear only enough evidence from the state to determine whether the crime -- IF it could be proved beyond a reasonable doubt -- would make out a felony conviction. If so, they vote a true bill of indictment.
As for that felony indictment, typically it does take several weeks for a newly indicted case to be calendared for his arraignment on the felony.
It looks like he'll be appointed a lawyer on the 4th, which is when his constitutional right to counsel formally accrues. At that point his lawyer will interview him, discuss his case and try to get his bail lowered.
However, if he's being wrongfully incarcerated, at any time while that's going on a lawyer can file a writ of habeas corpus to get him before the judge and ask why he's still being held this long without an arraignment. You can call the public defender's office and ask them if he's being wrongfully held and if they can do a writ.
If they agree he's being held unconstitutionally and won't file a writ, your remedy -- apart from waiting til October 4 -- would be to find other pro bono assistance, which generally means contacting the ACLU and also calling local law firms that handle criminal matters and asking if they'll take the matter on. Unfortunately, the overwhelming majority of pro bono criminal lawyers are public defenders, and once you rule them out, finding another free lawyer is very difficult. The ACLU does have branches all over the country, and they should be able to steer to someone local who may be able to offer you assistance.