Complex sentence: Wesker, then one of Umbrella's top research scientists, orders his personnel to dispose of Lisa; however, she survives her execution, and wanders the mansion's grounds in hopes of finding her mother.
Split into simpler sentences: Wesker, then one of Umbrella's top research scientists, orders his personnel to dispose of Lisa. However, she survives her execution, and wanders the mansion's grounds in hopes of finding her mother.