Counter-terrorism police have been searching a home in Birmingham over the weekend where friends of Westminster attacker Khalid Masood lived.
Officers were seen by neighbours on Saturday at the maisonette in Bredon Croft, Hockley, less than 200 yards from a property Masood had lived in until the end of 2016.
Specialist police search teams were still at Bredon Croft home on Sunday removing bags of evidence.
Meanwhile, a 58-year-old arrested in Birmingham remains in custody.
The hunt for the 52-year-old Masood's accomplices saw 11 people held after raids across the country.
Kurt Cochran and his wife Melissa had been visiting London from the US to celebrate their 25th wedding anniversary and were due to fly home.
A 30-year-old man was arrested in Birmingham on Sunday on suspicion of preparing terrorist acts.
Dozens of women gathered on Westminster Bridge to form a human chain in a show of solidarity with the victims of Wednesday's terror attack.