A cryptic Facebook post appeared on the page of one of the suspects in the Parsons Green Tube train attack days before the bombing took place.
On Tuesday, September 8, just three days before Friday's attack at Parsons Green Station, a message in Arabic appeared on the page apparently belonging to Yahyah Farroukh, 21.
When translated, the post reads: "Which places took you from me?"
Farroukh, 21, was arrested by officers outside a fried chicken shop in Hounslow, west London, on Saturday night.
The Daily Mail reports that on June 29, a few days after the London Bridge terror attack, Farroukh lost his father in Syria.
According to the Facebook profile, Farroukh is from Damascus, capital of Syria and still a stronghold of President Bashar al-Assad, although violent clashes with rebels in the surburbs have been reported in recent months.
It says he studied English for speakers of other languages at West Thames college near his home in Stanwell, Surrey, which was searched by police on Sunday.
Pictures of Farroukh posing with family and in front of tourist spots in London are shown on the profile, which also claims that he worked for a London events company.
Farroukh is believed to have been fostered by Penelope and Ronald Jones, aged 71 and 88 respectively, who previously received MBEs for services to children and families.
A homemade device partially exploded on a District Line train bound for central London at 8.20am on Friday, injuring 30 people.
Farroukh is one of two people arrested as part of the police probe into the attack.
CCTV showing a man carrying a Lidl bag just before the explosion on the Tube at Parsons Green has also been given to police.
The Islamic State (IS) terror group has claimed responsibility for the attack through its Amaq news agency, according to the US-based Site Intelligence.