Required to wait 30 days or required to comply within 30 days? I just can't see any reason any provider would purposely wait 30 seconds, in an investigation such as this. Their customer is dead. LE calling it under suspicious circumstances. Seems to me that's all it would need for the deceased customer's records to be handed over.
Several years ago (2007), when a local woman was lost, they were able to get cell records within 7 days.
http://www.seattletimes.com/seattle-news/last-phone-call-steered-search/