I don't mean to be PC; far from it - but I don't think you can argue with the description.
Do you think they are not mentally disturbed?
Seriously though, what are we to do.
One of the priest killers - from BBC report:
"The suspect named as Adel K, aged 18, is reported to have been in custody and then placed under a control order, and had tried to enter Syria twice."
Seems pretty clear cut.
You may say he should have been kept in custody for ever but can that be done?
German attacks:
"On 18 July, a teenage Afghan refugee hacked at passengers on a train in Wuerzburg with an axe and knife, wounding five. He was shot dead by police.
On 22 July, a German teenager of Iranian heritage shot dead nine people in Munich before shooting himself dead.
On 24 July, a 21-year-old Syrian refugee killed a woman with a machete and wounded five other people as he fled before being arrested.
Later that day, a 27-year-old Syrian whose refugee application had been refused blew himself up outside a bar in Ansbach. Fifteen people were wounded."
If you have a sensible way of preventing these, I am sure the authorities will be grateful.
I know you will say they shouldn't be here (in Europe) but a lot of attacks have been by people born here.