It seems likely that Mr Foster was an over-controlled individual who could not cope with the drastic loss of face that was about to occur. He had already lost his business – the loss of his home and millionaire lifestyle was imminent.
At this stage it is difficult to diagnose a mental illness without further information but it is reasonable to assume that he was clinically depressed, albeit undiagnosed.
It is highly likely he would not have discussed it with his GP or family members. Many men living his type of lifestyle find it difficult to express or display personal weakness.
It is likely that he could not cope with the loss and, because of that, he held an unrealistic but common attitude; he felt he had to stop his family suffering the inevitable drastic loss of status. He was about to lose his house, his horses and the ability to pay the expensive school fees at his daughter's private school. He also wouldn't have been able to afford the cost of the millionaire lifestyle that he was accustomed to.
He could be regarded as an over-controlled personality, who would not have been experiencing an active psychotic episode.
Mr Foster is different from the spree killers who kill their victims in one explosive outburst as shown by Michael Ryan at Hungerford when he shot dead 16 people, or Thomas Hamilton who killed 16 children and a teacher at Dunblane Primary School. His behaviour appears to have been very thorough and well planned rather than the actions of an impulsive or explosive personality.
The fact that we remember the names of Ryan and Hamilton is because of the brutality of their acts and how infrequently something like that occurs. I think we may remember Christopher Foster's name, too, because of how rare his actions were and how much publicity it attracted. I don't think he would want to be remembered though. He was ashamed and embarrassed by his financial situation. Being remembered will be the last thing he wants.
It is very rare to speak to a spree killer because, by their very nature, they want to go out spectacularly, in this case Mr Foster was able to take his own life and not be dependent on others.
Suicide following murder is more common than the public realise. Classic cases include the cult leaders who murder their disciples or followers and then kill themselves, for example, the Jonestown Massacre; other cases include "mercy killing", where one partner kills the other to relieve them of pain or desperation.
Another type is the aggrieved parent who kills their children to stop the other parent having access to their children and then kill themselves. But Mr Foster doesn't fit into any of these categories. What he did is so rare that we don't have a name for it.
It should be remembered that most individuals kill only once, it is unusual to kill twice and extremely rare to kill three times. That makes Mr Foster's crime all the more rare and gruesome.
The author is senior lecturer in forensic psychology at Manchester Met University