HUDSON, N.Y. (AP) _ A jury Tuesday acquitted a teen-ager charged with murder after confessing that he shot and killed four family members.

Wyley Gates, 18, also was found innocent of criminal possession of a weapon but convicted of second-degree conspiracy, which carries a maximum sentence of up to 25 years in prison. Sentencing was set for Nov. 9.

Gates, a former high school honor student, was charged with eight counts of second-degree murder in the Dec. 13 killings of his father, brother, cousin and his father's girlfriend, who lived with the family.

The Columbia County jury returned its verdict after 53 hours of deliberations over six days. The trial began Aug. 17.

Defense lawyer Charles Wilcox argued that Gates was a ''sick'' boy who confessed to the crimes out of a warped sense of loyalty to friends who actually pulled the trigger.

However, Wilcox would not speculate on who shot the family.

''There was some justice done tonight,'' Wilcox said. ''The jury concluded the confession was taken in violation of Wyley Gates' constitutional rights.'' Wilcox argued that police violated Gates' rights by not allowing a lawyer to be present while the youth was questioned in preparation for a lie detector test.

Gates was charged with killing his father, Robert Gates Sr., 39; his brother, Robert Gates Jr., 19; his cousin, Jason Gates, 3; and his father's girlfriend, Cheryl Brahm, 36.

As the verdict was read, Gates remained stone-faced as he has been throughout the 10-week trial. But he smiled later as he shook hands with Wilcox and assistant Joan Yowe.

Gates had no comment as he left the courtroom.

District Attorney Eugene Keeler, who was visibly disappointed as the verdict was read, pushed through a throng of reporters and would not answer questions.

According to testimony, the killings were plotted at least two months in advance. Keeler argued that Gates hated his father and resented Brahm. Gates' parents were divorced and his mother lives in California.

Miles McDonald, a former Gates' classmate, testified that Gates intimated last year that he had a plan to kill his father. McDonald said Gates told him and another youth, Damian Rossney, of the plan in their high school computer room.

Prosecutors say Rossney helped plan the killings and charged him with eight counts of second-degree murder. McDonald was granted immunity.