Baltimore prosecutors delayed a violation-of-probation hearing Wednesday for Lavelva Merritt, who was charged with murder in the stabbing death of a Johns Hopkins University researcher last year but pleaded guilty only to robbery-related crimes in May as part of a deal.

The hearing is now set for late September, so she can first be sentenced in the robbery case.

One of Merritt's public defenders, Robert Cummings, agreed to the delay after consulting privately with the prosecutor and judge, saying that it was "possibly to the benefit of my client to do so."

He declined to elaborate, as did the Baltimore state's attorney's office.

Prosecutors are watching to see if Merritt follows through on a promise to testify that her lover, John Wagner, fatally stabbed Stephen Pitcairn last year as the young scientist walked home along St. Paul Street inCharles Village.

Wagner's murder trial in the Pitcairn case is scheduled for August, and Merritt, 25, was offered a deal in exchange for her testimony against him, according to a video recording of the May proceeding previously reviewed by The Baltimore Sun. She's expected to say Wagner, 38, stabbed Pitcairn while they both robbed him.

If she complies, Merritt will receive a 15-year sentence, with another 15 years suspended, for the robbery-related crimes, and the murder charges against her will be dropped.

The robbery violates her probation from an earlier drug case, however, and she could get more time for that — up to six years, attorneys said.

On Wednesday, Circuit Judge Kendra Y. Ausby granted the postponement request and set the new hearing date for Sept. 30. She added that her court is "not inclined to postpone again."

It's up to Ausby to determine Merritt's sentence in the probation case if she's found guilty, though prosecutors can offer recommendations, including whether they believe that the term should be concurrent with or consecutive to any others.

Pitcairn's death became a mobilizing issue during the city state's attorney's race. Challenger Gregg L. Bernstein, who unseated Patricia C. Jessamy, made it part of his campaign platform, vowing to crack down on violent repeat offenders like Wagner, who had prior convictions for violence but had escaped significant jail time.