Complex sentence: The CHP officers had stopped several times earlier and spoke with Miss Graham but did not stop again when they saw her talking with the young man; the patrolmen assumed he was family, the help for which she'd called.
Split into simpler sentences: The CHP officers had stopped several times earlier and spoke with Graham but did not stop again when they saw her talking with the young man. The patrolmen assumed he was family, the help for which she'd called.