A mysterious powder was found on the gas tanks of Felipe Massa's and Kimi Raikkonen's cars on May 21, six days before the Monaco race, the Gazzetta dello Sport and the Italian news agency ANSA reported.
The parts were replaced before the race and the powder was sent to the police to be examined.
Massa finished third in the race and Raikkonen was eighth.
ANSA reported that Stepney was disappointed that he was not promoted to technical director when Ross Brawn left the team after last season. Stepney criticized Ferrari in an interview with a British newspaper and the team responded by not sending him to races anymore.
Ferrari said it has also started an internal investigation against Stepney, but that he is still employed by the team. It would not provide information on his whereabouts.
Ferrari is struggling to keep up with McLaren-Mercedes this season.
McLaren drivers Lewis Hamilton and Fernando Alonso are 1-2 in the driver's standings, while Massa and Raikkonen are third and fourth. In the team standings, McLaren holds a 35-point lead on Ferrari after seven of 17 races. Pravda.ru