Police remain at the home of the mother of Westminster terrorist Khalid Masood on Friday evening.
In the wake of the attack detectives say they will leave no stone unturned in their hunt for information.
The home near the rural village of Trelech in Carmarthenshire is the home of the killer's mother named as Janet Elms.
Police have stressed she is not a suspect.
Two uniformed police officers were on duty on Friday outside a bungalow in Banbury, Oxfordshire that is believed to be the home of Paul Ajao, Masood's half-brother.
The single lane track leading to the farmhouse in Trelech was blocked by a police van and officers on Friday.
One of the doors to the house was open but there was no sign of the occupants.
A mechanic at the garage in the tiny village said the couple had lived in the house for about 15 years and were "good people".
He said: "He (the husband) is sick with cancer. I expect she's under enough strain as it is without what her son's done."
Khalid Masood was once a keen schoolboy footballer grew into a troubled adult in and out of prison for a string of violent crimes including slashing a man with a knife after a boozy pub row with "racial overtones".
Questions remain over where the man born as Adrian Russell Elms to a single mother in Dartford, Kent on Christmas Day 1964 was radicalised.
Reports suggest it could have been during one of his stints behind bars, while others point to time allegedly spent working in Saudi Arabia, home to some of the most virulent Islamic extremism.
The 52-year-old's family moved around during his youth.
His mother Janet Elms is believed to have married Phillip Ajao in 1966 and the killer called himself Adrian Russell Ajao as one of his many identities over the years.
The family moved to St James Park in upmarket Tunbridge Wells, Kent, where an elderly neighbour on Friday said she remembered them as a pleasant, normal family who later moved to Wales to start a chicken farm.
Masood's criminal career dated back to 1983 and included convictions for assault, GBH and possession of an offensive weapon.
At some point after his radicalisation he came to the attention of MI5 but only as a peripheral figure.
The killer most recently appeared to be based in the West Midlands, but also spent time in London, Sussex and Luton.
James Crichton-Smith reports: