Suffolk County District Attorney Daniel F. Conley’s office today argued against sentence reductions for two of Boston’s most notorious murderers in hearings before a panel of Superior Court judges.

Assistant District Attorney Charles Bartoloni told Judges Barbara Dortch-Okara, Wendie Gershengorn, and Peter Lauriat that five consecutive life terms was the appropriate sentence for SINY VAN TRAN (D.O.B. 9/9/57). Tran, a one-time Boston resident, was convicted at a 2005 trial of the first-degree murders of Chung Kand Luu, 26; Chung Wah Son, 58; Van Tran, 31; Man Cheung, 55; and David Quang Lam, 32, in the basement of 85 Tyler St. in the early morning hours of Jan. 12, 1991.

A short time later, First Assistant District Attorney Josh Wall argued that JOSEPH COUSIN (D.O.B. 8/9/84) should serve the consecutive sentences imposed following his convictions for the second-degree murder of 10-year-old Trina Persad, unlawful possession of the shotgun with which he shot her, and receiving the stolen motor vehicle from which he fired it on the evening of June 29, 2002.

Both defendants appealed their sentences to the Appellate Division of the Superior Court, which determines whether a convicted defendant’s sentence was in their opinion “reasonable at the time it was imposed.” If the panel of three judges finds it to be reasonable, then they dismiss the appeal; they also have the authority to reduce a sentence they believe to be excessive or increase a sentence they find lenient.

Speaking in the Tran case, Bartoloni called attention to the fact that six victims were playing cards in a basement when they were set upon by the defendant and two others. Tran, NAM THE THAM (D.O.B. 10/13/58), and a third man announced a robbery and ordered the victims to the floor.

“The victims complied,” Bartoloni said, but the assailants shot all of them in the head anyway. “This was after many of the victims pleaded for their lives.”

Five of the men died of their injuries. A sixth miraculously survived and was able to identify the gunmen. They were apprehended in China in 1998, rendited to the United States in 2001 after protracted diplomatic negotiations, and convicted of all charges on Oct. 5, 2005.

The mandatory penalty for first-degree murder is life in prison without the possibility of parole. Tran did not appeal that sentence but rather the trial judge’s decision to make the sentences consecutive rather than concurrent.

In the Cousin hearing, Wall told the court that the trial judge acted appropriately when she sentenced the defendant to consecutive prison terms.

“He committed three separate and distinct crimes,” Wall said. “Each crime led to the next.”

Cousin was convicted last fall of directing a fellow gang member to get a stolen car, obtaining a shotgun without a license, and firing the shotgun at a fellow gang member from the car while the young Persad stood a short distance from him. Persad suffered a massive and fatal injury to her face and head.

After trial, Cousin was sentenced to 8 to 10 years for the car, 4½ to 5 for the gun, and life with the possibility of parole after 15 years for the murder. Wall told the appellate panel that those sentences were appropriate, as was the trial judge’s order that they be served back-to-back rather than at the same time.

“There is nothing in the facts of the case or the defendant’s background to suggest that this sentence was excessive,” Wall said. “There was no mitigation whatsoever.”

Tran was represented by attorney Janet Pumphrey and Cousin by attorney William White. The appellate judges took no action today and indicated that they would notify the parties of their decision at a later date.