Typically state prosecutors can bring charges in two ways. He can file an Information with the Court which is the charging documents. The defendant is arrested, if not already, and Arraigned (enters guilty or not guilty plea). Then the will have to be a preliminary hearing or probably cause hearing. There is sort of a mini-trial and the prosecutor must present just enough evidence to convince the judge that there is probable cause for the cause to proceed. The defense can defend at the preliminary hearing. Often preliminary hearings are waived by the defendant. The prosecutor can also bring charges by presenting evidence to a grand jury. This is done in secret and the defense is not allowed to attend or even know what goes on. If the grand jury finds probably cause of the crime they return a "true bill" or a "no bill" if they don't find probably cause. Then this "true bill" is turned into an Indictment that is the charging document filed with the court. Since the grand jury has already found probably cause, no preliminary hearing is required. In this case the DA used a grand jury. Typically prosecutors prefer informations because its just easier and cheaper than impaneling a grand jury. The defense attorney is insinuating that the DA is afraid to have his evidence challenged in a preliminary hearing. Its probably just blustering on the part of the defense attorney.
FYI, in the federal systems, charging by Information is not allowed and all charges must be brought through a grand jury.
