I will try to give a bit of a background from a pharmacist's perspective:
Benzodiazepines at proper doses don't generally do this.
However:
Short-acting benzos at higher than recommended doses can cause memory issues and behavioural abnormalities where people do strange things they don't even remember doing during sleep or under the influence of the drug.
One of these ultra short acting benzos, triazolam, was actually withdrawn from the UK market because of this, because it was doing these things to people even at recommended doses.
http://articles.latimes.com/1991-10-03/news/mn-4409_1_halcion-sleeping-pill
If you read that article, you'll see that one lady even killed her mother and didn't remember doing it.
If Cornell had taken too much Ativan, this might be the reason. At regular doses I don't think this happens.