William Concepcion Sablan, 37, termed "borderline retarded" by his attorney during his trial, was found guilty of first-degree murder this morning by a federal jury.

Sablan and his cousin, Rudy Cabrera Sablan, 42, were charged with murdering Joey Jesus Estrella, 33, by strangling him with a headphone cord, cutting his throat 60 times with a contraband plastic razor, and opening his abdomen and removing his organs. Estrella bled to death.

The three men shared a 7-by-11-feet cell in the "special housing unit'' of the federal prison in Florence. Inmates are kept there if they need to be protected from other prisoners or if they have violated prison rules.

The jury will return Monday to hear arguments whether Sablan should be executed for his crime.

Attorneys for both sides declined comment following the verdict.

Estrella was slain on Oct. 10, 1999 and Rudy Sablan still is awaiting trial for his part in the crime.

William Sablan was serving time for a series of convictions in his native Saipan, the capitol of the U.S. Commonwealth of the Northern Mariana Islands.

Sablan, one of only two men in Colorado facing the federal death penalty, assaulted a family at knifepoint in 1984, court records indicate. In another case, he was among a group that tied up a shop owner and tried to strangle him with a telephone cord.

Sablan also has convictions for robbing two Japanese men on a golf course and taking four Chinese men hostage during a prison riot.