(CNN) A Los Angeles police officer has been arrested on suspicion of committing two rapes over the past four years -- the oldest of which was linked to him through DNA records while he was being investigated in the other case, prosecutors say.

William Rodriguez, 33, was arrested Tuesday on two felony counts of forcible rape, and is expected to be arraigned Thursday, the Los Angeles County district attorney's office said.

Rodriguez, a 10-year veteran of the Los Angeles Police Department, initially was accused of one assault -- allegedly raping a female acquaintance at his home on November 1, prosecutors say.

While being investigated in that case, investigators checked his DNA against the state database. That matched him with evidence in an unsolved sexual assault of a female in 2015, the district attorney's office said.

Rodriguez was off-duty during both assaults, according to the district attorney's office.

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