ST. LOUIS (AP) _ A boyhood sighting of a tornado first sowed ``Twister'' producer Steven Spielberg's interest in tornadoes, the media mogul told a jury, saying he never saw a St. Louis screenwriter's script about the storm chasers.

Spielberg testified Friday during the copyright infringement case filed by screenwriter Stephen Kessler, who seeks all the profits from the 1996 hit.

Kessler alleges that Spielberg, along with Michael Crichton and wife Anne-Marie Martin, who wrote the ``Twister'' script, took his screenplay, ``Catch the Wind,'' and turned in into ``Twister.''

Kessler's lawyers said the movie earned more than $150 million. Spielberg estimated his agency made $20 million to $80 million from the movie about tracking devastating tornadoes in Oklahoma.

Spielberg told the 10-member jury that he had never seen or heard of Kessler's script.

While growing up in New Jersey, Spielberg said he once saw a tornado near his house. His mother exclaimed, ``There's a twister,'' and with young Steven and one of his sisters, hopped in their car and chased it down the road, Spielberg said.

``I've had dreams about tornadoes after that moment,'' he said.

Spielberg said he never read ``Catch the Wind'' even after Kessler sued him in 1996.

``I wanted to be able to look at the jury here today and say I've never read this script,'' he said.

Kessler's attorneys say copies of Kessler's ``Catch the Wind'' were sent to representatives of Spielberg and Crichton after Kessler became a semifinalist in a 1989 screenwriting contest.