Eugene Coleman, a 39-year-old Forestville man who pleaded guilty to drowning his 11-year-old stepdaughter in a bathtub and to raping another girl, was sentenced to life in prison plus 17 years yesterday in Prince George's Circuit Court by Judge Howard Chasanow.

Last February a jury found Coleman guilty of raping a girl on July 1, 1982, and leaving her naked, bound and gagged in the basement of his Forestville home while he went upstairs and drowned his stepdaughter, Leticia, in the bathtub. Coleman was unemployed at the time and his wife had left the house for a job interview. Coleman pleaded not guilty by reason of insanity.

A month after the conviction, defense attorney Joseph Finlayson Jr. said that he made errors during the February trial and Chasanow granted a new trial in which Coleman pleaded guilty to first degree murder and second degree rape. Yesterday Chasanow sentenced Coleman to life for the murder, 12 years for the rape and five years for false imprisonment of the rape victim. Each term is to be served consecutively. Coleman could be considered for parole in about 15 years.

During the trial, psychiatrists said that Coleman did have some sort of mental illness, but they did not agree on the exact diagnosis. Chasanow told Coleman in court yesterday "your sickness does not rise to the level of legal insanity." However, the judge said that he would recommend that Coleman be evaluated.

Chasanow also chastised the state's attorney's office and the mother of the girl for not acting to prevent Coleman from engaging in sex with the girl who had been raped. Chasanow said police were informed in 1979 that Coleman had sex with the girl

Coleman's wife, Carolyn, 31, a computer operator, said that she was not satisfied with the sentence. "He should rot in jail," she said, adding, "I think the system stinks, but I'm glad it's over." She said she plans to divorce Coleman.