Labour MP Jo Cox has died after being shot and stabbed in street by a man reportedly shouting "Britain first".
The alleged gunman has been named locally as Tommy Mair, 52, who neighbours have described as "a loner".
Officers were seen searching his house in Birstall, near the scene of the brutal attack.
Ms Cox, a 41-year-old mother of two, was left lying in a pool of blood on the pavement after her assailant shot and stabbed her outside her advice surgery in the West Yorkshire town.
Police said a 52-year-old man was arrested in connection with the attack, which happened near the town's library.
Mair's house was sealed off by police who were guarding the property as forensic officers worked in the garden.
Neighbours said he had lived there for more than 30 years - on his own for the last two decades since the deaths of his mother and grandmother.
They did not think he had a job or drove a car and described how he would do gardening chores for local people.
One neighbour, David Pickles, said: "He's lived there longer than me and I've lived here since 1975.
I didn't know Jo Cox but by all accounts she was a brilliant young MP. And today she was just doing her job. My heart breaks for her family
— Nicola Sturgeon (@NicolaSturgeon) June 16, 2016
"I still can't believe it. He's the last guy I would have thought of.
"He's just quiet. He kept himself to himself.
"He lived by himself. He's been on his own for about 20 years.
"I've never seen a lot of people visiting or anything like that, but he likes gardening.
"He did a lot of people's gardens round here. But he did it quietly."
THOMAS MAIR
Mr Pickles said he did not know of any connection between his neighbour and Ms Cox.
Another neighbour, who did not want to be named, said: "We've known him quite a lot of years.
"I've known him since I was young. He lived with his grandmother in that house, she died a few years ago.
"He was a bit of a loner. It's a bit of a shock - he did everyone's gardens.
"I can't say a wrong word about him, he was so quiet.
"It's come as a shock to everybody."
One resident, who also did not want to be named, described Mr Mair as "keeping himself to himself".
He said: "He had lived there for years and years, I don't know much about him.
"I would say hello to him but you didn't get much out of him. He seemed really quiet."
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