The terrorist behind the Westminster terrorist attacks, who killed four people by running them down with a car and stabbing a policeman. had allegedly warned his family of his impending death.
Khalid Masood reportedly said "You will soon hear of my death, but don't worry… I will be in paradise" during a phone call seven days before he committed the atrocities.
One sees this pattern more often. A Muslim commits to an atrocity where he'll be killed but before that he settles his family and financial matters. The Florida night club shooter had transferred his property to his wife -- she, at the very least, had an idea that something horrible was going to happen but didn't bother with the police. Here, the family knew a week in advance that Masood will be going full Jihad but, again, they didn't feel the need to call the cops.
This is one reason why such Islamic terrorists flourish -- their "moderate" families simply look the other way.