An Roslindale teen remains held without bail today following his indictment for the murder of one man and the attempted murder of another on board an MBTA bus last year, Suffolk County District Attorney Daniel F. Conley said.

KIM GROSS, Jr. (D.O.B. 12/7/92) was indicted March 9 on charges of first-degree murder, armed assault with intent to murder, and aggravated assault and battery with a dangerous weapon for the Nov. 2, 2010, stabbing death of 21-year-old Richard Allen and his 18-year-old friend shortly after they boarded a Route 44 bus in Roxbury.

In recommending that Gross continue to be held without bail, Assistant District Attorney John Pappas of Conley’s Homicide Unit told Suffolk Superior Court Clerk Magistrate Connie Wong that the bus was travelling its regular route that morning from the Jackson Square MBTA station to Ruggles station.

Gross and a male friend boarded the bus shortly after it left the Jackson Square MBTA station, Pappas said. The two men took seats in the back of the bus, where “the defendant sat on the very back row of seats and [his friend] sat a short distance away to the defendant’s right on a bench of three seats.”

At the bus stop prior to Waumbeck Street and Humboldt Avenue, Pappas said, Richard Allen got on the bus with the surviving victim and another friend.

“After paying their fares, those three people walked to the rear of the bus as well.”

The rear of the bus featured a row of seats along the back wall facing forward and two sets of three seats facing inward from the left and right walls of the bus. Allen took a seat on the back bench to Gross’ left. The 18-year-old victim sat in a bench of three seats opposite Gross’ friend. The third man in Allen’s group remained standing in the aisle between the three bench seats, Pappas said.

Moments after reaching the rear of the bus, Pappas said, Allen’s friend who was standing in the aisle “exchanged words with the defendant who had a white napkin covering the bottom portion of his face.”

Allen was sitting closest to the defendant during the verbal exchange, Pappas told the court. “As the verbal exchange played out, the passenger sitting right next to the defendant was keeping an eye on the defendant’s right hand, fearful that he may pull a gun out.”

“As the passenger made these observations, he observed a very noticeable and significant burn type scar on the back of the defendant’s right hand,” Pappas said. “Medical records secured during the course of the investigation confirm that the defendant was treated for serious burns sustained in an accident as far back as 1999.”

It was at that point, the prosecutor said, that Gross “proceeded to plunge the blade into Richard Allen’s chest with such force that it went through his aorta and esophagus. The wound he inflicted was obviously fatal. The defendant then went after [the 18-year-old victim] who was closest to him, stabbing him in the arm and leg.”

Pappas told the court that the stab wound to the victim’s right arm “resulted in a complete laceration of the median and ulnar nerves, requiring surgery and – at least at this point – loss of function to his right arm.”

During the mayhem, Pappas said, the friend of the two victims fled from the bus. After fatally stabbing Allen and seriously wounding the 18-year-old victim, Gross also fled from the bus and the area.

The days and weeks that followed were marked by extensive investigation by Boston Police homicide detectives, MBTA Transit Police detectives, and Suffolk prosecutors into data collected from the bus’ fare box, witness accounts, and other evidence including the defendant’s own phone calls.

Shortly after the stabbings, Pappas said, Gross allegedly used his cellular phone to call a faculty member at his school, saying that he was at home sick and would not be in school that day. Around the same time, he also allegedly called his girlfriend and told her he was home sick.

Analysis of those cell phone records, however, indicate that Gross was nowhere near his Roslindale home, the prosecutor said.

“Instead,” Pappas told the court, “the phone records show that both calls were made from the Roxbury section of Boston in the early morning hours of Nov. 2, 2010, shortly after Mr. Allen had been fatally stabbed and [the 18-year-old victim] had been seriously wounded.”

Gross was arrested Feb. 11 and has been held without bail since that time.

Catherine Rodriguez is the DA’s assigned victim witness advocate to the case. Gross is represented by attorney James Greenberg, and is expected to return to court on May 3.