Erik and Lyle Menendez on trial in November 1995

LOS ANGELES (CNN) -- An appellate court has affirmed a judge's ruling in the 1996 murder case of Erik and Lyle Menendez by denying the brothers a new trial, according to prosecutor David Conn.

The brothers had appealed the ruling by Superior Court Judge Stanley Weisberg, contending he had erred in several of previous rulings. Their appeal was denied Friday.

Lyle, 28, and his brother, Erik, 26, were convicted of first-degree murder for the August 1989 shotgun slayings of their entertainment father, Jose, and their mother, Kitty.

In 1994, separate juries were unable to reach a verdict in the case. A single jury heard the second trial in 1996. The brothers were convicted and sentenced to life in prison without the possibility of parole.

The brothers claimed that they killed their parents after suffering years of abuse. But prosecutors argued that the brothers killed to get the family money: $14 million.