BOSTON -- After 10 days of deliberations, a Middlesex Superior Court jury said they could not reach a verdict in the retrial of former Harvard graduate student Alexander Pring-Wilson accused in the 2003 stabbing death of a Cambridge man.

On Monday, the jury said they were deadlocked but the judge asked them to continue deliberating. On Friday, the jury said they were still hopelessly deadlocked and a mistrial was declared. One juror who did not want to be identified said the jury deadlocked 10-2 in favor of conviction.

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

Prosecutors said they will put Pring-Wilson on trial a third time.

"We will honor the memory of Michael Colono by continuing to fight for justice on behalf of him, his family, and the Commonwealth. We fully intend to retry this case," Middlesex District Attorney Gerry Leone said in a statement.

"We are making progress, and we're ready to do it again," defense attorney Peter Parker said.

Colono's mother and sister did not speak to reporters as they left the courtroom.

Pring-Wilson, a Colorado Springs, Colo., native who was studying for his master's in Russian and Eurasian studies at Harvard University, 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.

At the time of the fight, Colono, a father and a cook at a Boston hotel, was on probation on charges of drug possession and malicious destruction of property.

Saying the stabbing was in self-defense, Pring-Wilson's attorney said Colono was the aggressor and teamed up with his cousin to beat Pring-Wilson to the ground on a Cambridge street.

"How long was he supposed to take it and take it some more? How long was he supposed to do nothing but hope they stopped on their own before the next blow killed him or turned his brains to mush?" Parker asked during the trial.

During the fight, Pring-Wilson stabbed Colono several times in the chest, including in the heart, with a knife, prosecutors said.

"Alexander Pring-Wilson had a Spyderco military folding knife in his pocket and he was ready and willing to use it," prosecutor Adrian Lynch said.

Pring-Wilson was sentenced to six to eight years in prison after his original conviction.

He has been out on bail since that conviction was overturned in 2005. Unlike previous bail restrictions, Pring-Wilson will be allowed to travel to Colorado for the holidays. It will be the first time he has returned to Colorado since the stabbing.