BOSTON -- A Middlesex Superior Court jury told a judge on Monday that they are deadlocked and unable to reach a verdict in the second trial of former Harvard graduate student Alexander Pring-Wilson in the 2003 stabbing death of a Cambridge man.

The judge told the jury to return to the courthouse on Tuesday for further instructions.

It was the second trial for Pring-Wilson, 29, in the fatal stabbing of Michael Colono, 18, during an April 12, 2003 street fight.

Pring-Wilson, 29, a Colorado Springs, Colo., native, was originally charged with murder in Colono's death, but a jury convicted him on a lesser charge of manslaughter in 2004. In June 2005, that conviction was overturned after his attorney successfully argued that evidence of the victim's violent past should have been allowed at trial.

The jury deliberated for six days before saying they were deadlocked. The judge is expected to ask them to resume deliberations on Tuesday.

If the proceedings end in a mistrial, the prosecutor will decide if Pring-Wilson will be tried for a third time.