Predicting propofol effect 'hard', says expert

An expert on the powerful anaesthetic blamed for Michael Jackson's death today told jurors that it is difficult to know the medication's precise effect on the singer because he had been given so much of it for his insomnia in the months before he died.

Dr Steven Shafer pointed out that Jackson had been receiving the anaesthetic propofol almost every night for more than two months, according to a police statement by Dr Conrad Murray.