IMOLA, Italy (AP) _ Race car owner Frank Williams and five other defendants were acquitted today of manslaughter charges in the 1994 death of world driving champion Ayrton Senna.

Judge Antonio Costanzo announced the ruling one year to the day after the six men were indicted.

By clearing all the defendants, the judge ignored a prosecution request for suspended one-year sentences for two defendants, Williams-Renault technical director Patrick Head and former team designer Adrian Newey.

The judge had been expected to grant prosecutor Maurizio Passarini's request to acquit Williams, the British owner of the Williams-Renault team for which Senna was competing when his car slammed into a concrete wall on the seventh lap of the 1994 San Marino Grand Prix. Prosecutors in their final arguments last month also moved for acquittal of the three race officials also charged.

The case represented the first time Formula One executives have been brought to trial in Europe for a racing accident. The governing body of motor sports feared an unfavorable ruling will discourage racers from competing in Italy.

The prosecution alleged that a poorly modified steering column broke as Senna entered the Tamburello curve on the seventh lap of the San Marino GP, causing the Brazilian to lose control of his car and slam into the concrete barrier.

Defense lawyers countered that the cause of the crash is unclear, and Williams _ whose team has dominated Formula One in recent years _ has said it might never be determined.

There were also charges that the course itself had maintenance problems. But in addition to Williams, Passarini asked acquittals for race organizer Federico Bendinelli, circuit manager Giorgio Poggi and race director Roland Bruynseraede.

The corner was remade and the circuit asphalt changed following Senna's crash.

The day before Senna's death, Austrian driver Roland Ratzenberger died in a crash during practice for the race. No charges were brought in that case.

Senna, known as much for a fiery personality as brilliance on the track, won 41 GP races in his career, second only to Alain Prost's 51. Senna won world titles with Team McLaren in 1988, '89 and '91.