BROWNSVILLE, Texas (AP) _ Four Texans drew sentences ranging from probation to 18 months in prison in the deaths of five illegal aliens asphyxiated inside a fumigated railroad car.

The defendants had been indicted on alien smuggling charges but pleaded guilty to lesser offenses in a plea bargain.

The victims, five people from Mexico, Honduras and El Salvador, died in October after being locked inside a trailer filled with tortilla flour. The flour had been fumigated with Phostoxin, an insecticide deadly to humans.

Under questioning Tuesday from U.S. District Judge Filemon Vela, Assistant U.S. Attorney John G. Crews said he had no proof the defendants actually put the aliens in the trailer.

After the sentencing, the prosecutor said a fifth person, a Houston resident who cannot be found, is believed to have locked the aliens in.

The judge sentenced Magdaleno Arcos Soriano, 34, to 18 months in prison, to be served after a 14-month sentence imposed in November in another alien smuggling case.

Eleutorio Amaya Torres, 35, who received probation in the previous case, received a 16-month sentence Tuesday. Amaya's wife, Jane Amaya, 39, was sentenced to six months. Mary Ann Martinez, 24, got three years' probation.

Ms. Martinez had pleaded guilty to misprision, or concealing knowledge of a crime. Amaya and Arcos Soriano pleaded guilty to witness tampering. Mrs. Amaya pleaded guilty to conspiring to smuggle aliens.