The arrested teenager is thought to have been a 'problematic foster child' who was raised in Sunbury-on-Thames, Surrey, by Penelope Jones, 71, and husband Ronald, 88.
A local councillor said the teenage suspect came to the UK aged 15 after his parents died in Iraq while a friend of the Joneses said the man's biological family did not agree with him moving in with Christian foster parents.
The couple's home was raided by armed officers on Saturday and a neighbour claiming a bomb had been found, although Scotland Yard quashed reports that 15 firearms were seized, a neighbour claimed.
Residents on the street said officers had been in the area since Friday night with one neighbour saying: 'I only had to open the door and I saw police everywhere.'
The Joneses have raised 268 foster children in the house over three decades and the last eight have been refugees.
Eight years ago the kind-hearted couple were awarded MBEs by the Queen for their services to children and families.
A family member has confirmed the Joneses are currently 'safe and well'.