A former Los Angeles police officer has been charged with felony lewd conduct with a minor and is being held in lieu of $250,000 bail. Police spokesman Cmdr. William Booth said Michael Casados, 40, a 17-year veteran of the force who was assigned to the Northeast Area Division, resigned Monday after his arrest. Deputy Dist. Atty. Michael Barton, who is prosecuting the case, said the acts with which Casados is charged took place over a six-year period. A preliminary hearing was set for April 21.