Investigators stated that Cullen may have caused patients to suffer, but that he appears not to realize this, contradicting his claims of wanting to save patients. Similarly, Cullen told investigators that although he often observed patients' suffering for several days, the decision to commit each murder was performed on impulse. Cullen told detectives in December 2003 that he lived most of his life in a fog and that he had blacked out memories of murdering most of his victims. He said he could not recall how many he killed or why he had chosen them. In some cases, Cullen adamantly denied committing any murders at a given facility, but after reviewing medical records, he admitted that he was involved in patient deaths.