Despite more than six weeks of sometimes conflicting testimony, the jury in Suffolk Superior Court deliberated for less than a day before finding Ismael Vasquez, 27, his 23-year-old brother Luis, Harold Parker, 31, and Scott Davenport, 31, guilty of first-degree murder.

Parker and the Vasquez brothers were also convicted of kidnapping Io Nachtwey, a recent arrival from Hawai'i who hung around Harvard Square with other young homeless people. The kidnapping charge against Davenport was dropped earlier today.

Luis Vasquez was also convicted of rape. All four face mandatory life term at their sentencing, scheduled for tomorrow morning.

A woman was escorted out of court after she began screaming and crying as the verdicts were read.

"Io Nachtwey was the ultimate innocent victim," prosecutor Patrick Haggan said. "She was known on the streets of Harvard Square as someone who didn't belong. She was described as an angel, like a child. She was brutally murdered."

Defense attorneys said they would appeal and criticized the jury for deliberating for just five hours after weeks of testimony.

The Vasquez brothers and Parker were the leaders of a fledging gang that Nachtwey and her friends had been recruited to join. Davenport was a heroin addict who was along for the ride because the other three defendants could get him drugs, his attorney said.

In closing arguments, Assistant District Attorney Patrick Haggan said Nachtwey was terrified as they drove to a railroad bridge spanning the river between Cambridge and Boston because she knew the men planned to kill her to send a message to a rebellious faction within the gang.

She first tried to jump from the moving car and then agreed to have sex with Luis Vasquez, the gang leader, in the desperate hope that he'd protect her, he said.

But the men had already decided to kill her, Haggan said.

"This was a cowardly, vicious and senseless murder and each and every one of the defendants wanted it to happen or chose to allow it to happen," Haggan said.

Key witnesses for the prosecution included two 21-year-old women, Ana White and Lauren Alleyne, who avoided life in prison by pleading guilty to manslaughter and agreeing to testify against the four others.

They were sentenced to 12 years in prison, and with time served are due to get out around 2010.

The women said Davenport stabbed Nachtwey a dozen times as Alleyne held her down and White held her hand over Nachtwey's mouth to stifle her screams. Then, they said, Luis Vasquez cracked nunchucks on her skull to silence her, and her body was rolled into the Charles.

Haggan said Nachtwey's boyfriend had led a revolt among the gang recruits. On Halloween night 2001, the recruits were ordered to steal valuables as a gang initiation, but Nachtwey's friends failed to bring back any loot. Parker and the Vasquez brothers killed her to send a message to the rebellious faction, he said.

Davenport's lawyer said the gang leaders got him to do the stabbing by threatening to also kill him.

"Scott Davenport was put in the position of having to decide whether he lived or he died," attorney John Courtney said.

But Parker's lawyer said Davenport was trying to deflect attention from the fact that he was Nachtwey's killer.

"Scott Davenport had the audacity to tell you he was the victim here," said attorney Jonathan Shapiro. "He wants you to take pity on him."

Ismael Vasquez's attorney described White as a "manipulative, deceiving sociopath" who laughed, joked and sang along with Alleyne in the back of a police cruiser after they were arrested.