Friday. ABC-TV’s one-hour special 10 to 11 p.m. A sit-down with the father, film director Peter Rodger, whose son, Elliot, 22, killed his three roommates and three others in Santa Barbara in May.

Parents of past mass murderers have refused interviews. This time, when George Stephanopoulos and Matt Lauer also tried, they, too, were refused. Rodger — and this was a first — wanted to talk. But only to Barbara Walters.

He said making police and officials understand mental illness “is now my mission” and the story’s “better served to a woman.” Not verbalized was, just maybe, speaking out might help expunge his own guilt.

Walters: “I had 100 questions . . . like, ‘How do you live with yourself when your son’s a mass murderer?’ ” Answer: “After you have a nightmare you wake up. Now I wake up and then I have the nightmare.”

Does he feel responsible? “There were warning signs . . . loners don’t make friends easily.”

So where do you place a grief-stricken father of a mass murderer dead son and ask: How do you feel? Not his home. Not the killing site. Not a sterile hotel. The venue? A quiet rented house in California.

Neither the boy’s birth mother nor stepmother would speak. Divorced Mr. Rodger did not cry. He, however, choked up telling about his second marriage’s ­9-year-old son, Jazz. “We had to tell him this brother he loved did something wrong.”

Unclear whether cops shot and killed Elliot or he took his own life. Clear is his YouTube manifesto of hate. Facing a camera attached to his car’s dashboard, with a macabre laugh, he said he had to kill blond girls, might even kill his stepmother and little brother.

Faced with these the father and birth mother raced to help their son. Too late.

Back story

No. 1. Following a dozen farewell parties in her honor after announcing retirement from “The View,” the show she created, Barbara was on vacation. With me. In Berlin. One afternoon we were lunching at lakeside café Die Fischerhutte am Schlachtensee. A cellphone rang.

Kids were flying kites. We were eating veal burgers. James Goldston, ABC News President, was calling for Barbara to do this sit-down.

Back story No. 2. Peter Rodger has a longtime friend. Simon Astaire. In the ’60s Astaire’s English father Edgar dated Barbara. Knowing his father’s high regard for Barbara, the younger Astaire told the shooter’s father: “You can trust her. My father did. He always said if she gives her word she keeps it.”

We all think we know our husbands, wives, friends, kids. To hear what Peter Rodger knew about his son, tune into ABC-TV Friday 10 p.m.

Odds & ends

Local Hamptons TV interviewer Judith Sleed to Alec Baldwin: “You always say no to doing my show.” Alec: “This time, it’s yes. I’ve been saying no to many things lately.” . . . NEWEST alliance? Israel, which numbers few friends, and China, which suspects most friends. Pariahs to much of the world, together they’ve made shalom. Many Jerusalem tourists are Chinese.

Helen Mirren played Linda Kenney Baden in HBO’s doc on Hollywood record guy, jailed Phil Spector whose blond ladyfriend actress somehow got offed in his home. This Linda, his New York lawyer, married to Dr. Michael Baden, respected coroner who’s testified on headline cases like Jon Benet and OJ’s slain wife.

Linda phoned to say she’s been busy. In a courtroom? No, behind a poker table.

An ex FBI guy taught her the game in September. Since December she’s been behind nine final tables. Just won Foxwoods championship. Came in seventh in a tournament. July 5, Vegas, she’s in a main event, a ladies world series of poker. Do well she grabs $10,000 and another world poker event seat in another place.

Both Michael Baden and I remain stunned.

Only in New York, kids, only in New York.