Members of a secret Prince George's County grand jury toured the county correctional center on Tuesday, as the investigation into how a jail inmate died appeared to be gathering speed, ABC 7's Brad Bell reported.

The grand jurors were given a complete tour and lunch, including, a corrections official confirmed, a look at the area where inmate Ronnie White died June 29.

The jail official also said grand jurors are routinely given a tour of the jail, and that Tuesday's visit was nothing unusual.

The visit, however, comes as prosecutors are preparing to bring evidence before a grand jury about White's death.

The grand jurors who toured the jail on Tuesday are not believed to have heard any testimony about the White case.

The 19-year-old was charged June 27 with the murder of Prince George's County police Sgt. Richard Findley. White was found dead in his cell less than 36 hours later. The medical examiner’s preliminary report ruled his death homicide by asphyxiation.

Since then, Maryland State Police investigators have reportedly focused on three correctional officers whose duties put them near White's cell.

A break for investigators may have come last week when one of the guards gave detectives a full interview.

The guard's lawyer says his client has not been called before the grand jury, however.

The other sitting Prince George’s County grand jury will meet on Thursday. Its schedule has not been made public.

The next major event in the investigation is expected to be the final medical examiner’s report on White’s death. When complete, it will be delivered to the state’s attorney.