LOS ANGELES -- Every explosion needs a spark, every conflagration a match. And all murders need a reason, even if that reason is madness.
So the prosecutors in the O. J. Simpson murder trial must explain why he did what they say he did.
They must explain why the smiling, affable man we see on television each day committed two acts of almost monstrous savagery.
And they have come up with an answer: the dance recital.
It was at the June 12, 1994, dance recital at which Simpson's 8-year-old daughter, Sydney, performed and nearly the entire Brown family gathered, that O. J. realized he was no longer wanted.
The family did not save a seat for him, did not invite him to dinner afterward and this caused him, the prosecution has argued, to snap.
Harlan Toplitzky was there.
"The recital was at Paul Revere Junior High School in Brentwood," he said. "They hold it every year. The families go, they watch the kids, and then everybody goes out to dinner."
There were 10 members of the Brown/Simpson families there that night, including O. J. and Nicole. But they did not sit together. And when it was over and everyone else headed for Mezzaluna, O. J. headed home for a burger with Kato.
"He had a very bizarre look in his eyes," Denise Brown, Nicole's sister, said of O. J. that evening. "It was actually kind of spooky. It was a glazed-over, kind of frightening [look], dark eyes."
Harlan Toplitzky puts it this way: "We walked into the auditorium, and just over to the right I saw Steve Garvey [the former L.A. Dodger]. He was standing with his wife, Candy, and talking to O. J. They looked animated. They looked happy."
Which is not the way the prosecution describes it. "He was in an ugly mood, morose, depressed, clearly fixated on his ex-wife," prosecutor Marcia Clark told the jury in opening statements. "He was not at all cavalier about losing Nicole."
"Not upbeat, not downbeat, I thought he was tired," celebrity leech Kato Kaelin testified at the preliminary hearing. Then Kaelin described how O. J. complained about the tight, short black dress Nicole had worn to the recital.
"If they are going to be grandmas, they can't wear those outfits," Simpson told Kaelin.
Nicole would never be a grandma, of course. In a few hours, she would be found murdered in that tight, short black dress.
"A little vacant, nonresponsive, I felt he was looking right through me and it scared me a little bit," Candace Garvey testified as to O. J.'s appearance at the recital.
She was then asked if Simpson appeared angry. "Yes," she said. "His jaw was set."
Harlan Toplitzky has this to say: "After the recital, we were going to go to Mezzaluna, but it was too crowded. So we went to the Gaucho Grill next door. And at dinner, my mom said: 'Didn't O. J. Simpson look a little upset tonight?' "
According to prosecutor Chris Darden, O. J. Simpson was more than a little upset that night.
"He was angry, he was depressed," Chris Darden told the jury during his opening statements. "The [Brown] family made clear he was not invited to dinner. And by not inviting him, it was a reaffirmation of what he had been told: That it was over. She [Nicole] was no longer in his control. He was obsessed with her. He could not stand to lose her. And so he murdered her."
Harlan Toplitzky provides the definitive description of O. J. Simpson that night: "He was looking out into space. He had a distant and disturbed look on his face. His eyes were almost bulging out. His eyes were bulging. He looked disheveled. He looked strung out."
Which leaves us with only one question: Just who the hell is Harlan Toplitzky?
His name is not on the defense or prosecution witness lists. He has not been subpoenaed. He has not been interviewed by anyone -- not even "Hard Copy" -- until now.
But Harlan Toplitzky, 17, a senior at Beverly Hills High School, proves what I have long suspected: There are not 4.1 million people in Los Angeles County. There are 4.1 million stories that have something to do with O. J. Simpson.
"My sister, Mari, is 9, and she was dancing that night at the recital, too," Toplitzky told me. "Seeing movie stars around here is not really that big a deal. It was Steve Garvey who really caught my eye. I'm a big baseball fan. And, well, O. J. is a little before my time. But I loved him in the 'Naked Gun' movies."
Beverly Hills High is possibly the most famous high school in America and not because of the many people in the entertainment industry who have gone there. (Wendy Finerman graduated from Beverly Hills High in 1978. In a few weeks, she will probably win the Oscar for co-producing "Forrest Gump.")
No, Beverly Hills High is famous for its swimming pool. And you've seen it. Yes, you have.
In the movie "It's A Wonderful Life" it opens up under the dancing feet of Jimmy Stewart and Donna Reed and dumps them into the water in the high school gym.
Called the Swim-Gym and built in 1939 by the Works Projects Administration, it is still in daily use.