ALBUQUERQUE, N.M. — A former Albuquerque Public Schools bus driver pleaded guilty Thursday to charges for multiple rape cold cases.

Ralph Martinez pleaded guilty to six counts of criminal sexual penetration. The charges stem from three different cases, between 1988 and 1991.

Martinez said he didn’t know the victims. They were between 18 and 59 years old at the time.

Special agents with the Bernalillo County District Attorney’s Office arrested Martinez in July. According to the DA’s office, a DNA investigation linked him to the assaults.

The investigators who cracked the case are with a special unit under the DA’s office that looks into sexual assault cold cases. They had the old rape kits and narrowed it down.

Agents reportedly collected DNA from Martinez’s school bus steering wheel, gear shift and switches. They found that it was a match.

Martinez was an APS bus driver for five years.

Martinez now faces up to 30 years behind bars. A sentencing date hasn’t been set yet.

According to the DA’s Office, this is the 13th cold case rape conviction in the past year that began with the work of the Sexual Assault Kit Initiative Team. They say, 30 minutes after Martinez pleaded guilty, William Spencer also pleaded guilty to raping four women in the Albuquerque area in 2016 and 2017.

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