Sirhan Sirhan, convicted of killing Robert F. Kennedy more than four decades ago, will remain in prison, after a parole board again denied him parole on Wednesday. Mr. Sirhan, who assassinated Mr. Kennedy at the Ambassador Hotel in Los Angeles in 1968, had originally been sentenced to death, but his sentence was commuted when the State Supreme Court ruled the death penalty unconstitutional. He has since been denied parole 14 times. In the lead-up to the hearing, Mr. Sirhan’s lawyer indicated that Mr. Sirhan did not remember shooting Mr. Kennedy, who had just won the California Democratic presidential primary.