A Soviet military tribunal Friday found the son-in-law of former President Leonid I. Brezhnev guilty of taking bribes and abusing his office and sentenced him to 12 years in a labor camp. Yuri Churbanov, who served as first deputy interior minister during Brezhnev's years in power, had systematically taken thousands of rubles of bribes instead of enforcing Soviet laws, said the judge, Army Maj. Gen. Mikhail Marov. The verdict came a day after the Kremlin ordered a memorial plaque removed from Brezhnev's former home and ordered all factories and schools named for him renamed (story on A3). The 52-year-old Churbanov could have received the death penalty. Churbanov, who married Brezhnev's daughter Galina in 1971, stood throughout the 31/2-hour procedure at the Soviet Supreme Court. He did not react to the verdict and sentence and declined to talk afterward to reporters.