LOS ANGELES (AP) _ The attacker in the near-fatal stabbing of actress Theresa Saldana began trial Thursday on charges of sending death-threat letters to the movie star and her rescuer.

Jury selection began in the trial of Arthur R. Jackson, 55, who faces six years in prison if convicted of sending the letters to Miss Saldana and Jeff Fenn, the water deliveryman who subdued Jackson and held him for police.

In the letters, Jackson said it was his ''divine mission'' from God to kill Miss Saldana for a future heavenly rendezvous with him. The Scottish drifter, who has a history of mental problems, entered the United States illegally in 1982 to stalk the actress.

Jackson was convicted of attempted murder after the March 15, 1982, knife attack outside her West Hollywood apartment. He was sentenced to 12 years in prison, which was halved for good behavior.

Authorities learned about the letters just weeks before his scheduled June 1989 release. The 16 felony counts of menacing the actress and Fenn were subsequently filed and he was ordered held without bail.

Once a jury is selected, trial should last about eight days, said Deputy District Attorney William W. Hodgman.