Complex sentence: Zehaf-Bibeau returned to his vehicle, which was parked on the south side of Wellington Street behind the memorial, and drove west along Wellington a short distance to Parliament Hill, where he abandoned his vehicle.
Split into simpler sentences: Zehaf-Bibeau returned to his vehicle, which was parked on the south side of Wellington Street, behind the memorial. He then drove west along Wellington a short distance to Parliament Hill, where he abandoned his vehicle.