A US tourist has revealed she posed for a photo with the police officer who tackled the Westminster terrorist less than an hour before he was killed.
The photo emerged as the fourth victim of the attack was named as 75-year-old Leslie Rhodes from Clapham, whose life-support machine was turned off on Thursday evening.
US tourist Staci Martin, who was visiting her son in London, had asked PC Keith Palmer to pose with her for a photo as she "liked his funny hat".
Forty-five minutes after the photo was taken, the 48-year-old officer died after confronting Khalid Masood - a Muslim convert born Adrian Russell Ajao - as he attempted to gain entry to the Palace of Westminster.
Mrs Martin told local US news station West Palm TV she later saw pictures of the officer on television.
"They put his picture up and I said, 'I think that's the guy' and my husband and daughter thought I was crazy. We just couldn't believe it," she said.
Describing PC Palmer as "very polite" Mrs Martin shared the last known picture of the officer on her Facebook page along with a timeline of her experience of the attack.
She added that she "feels obligated" to get the picture to the officer's family.
"They can cut me out of it, but I just want to make sure they have that of him.
"It was the hat that inspired the picture, but it's the man and what happened to him next that makes it unforgettable.
"You think if I had only been there a half an hour later in that exact spot. You can call it God or fate or whatever you want to call it, it's a little bit surreal for sure".
Hundreds of thousands of pounds have been raised since a memorial fund was set up for the fallen officer's family.
Three civilians also died after Masood drove his Hyundai into pedestrians on Westminster Bridge.
They have been named as teacher Aysha Frade, who was on her way to pick up her children from school; US tourist Kurt Cochran, who was celebrating his Silver wedding anniversary; and 75-year-old Leslie Rhodes from Clapham, south London.
Mr Rhodes, who is the fourth victim to be named by police, was on his way home from an appointment at St Thomas' Hospital when he was knocked down as he crossed Westminster Bridge.
A neighbour, Janet Pickthall, who lived in the same block of flats and had known Mr Rhodes for 44 years said he was "funny as anything, really lovely, genuine. One of the best people you could ever meet".
She described the retired window cleaner, who was still riding his bike at 75, as "always up and down ladders" cleaning his neighbours' windows.
She said: "It's a terrible way to go for someone as fit as him - he would have lived into his 90s."
Mr Rhodes, who suffered many broken bones when he was hit by the attacker's car, is believed to have gone into a coma straight away. The decision was taken to turn his life support machine off on Thursday evening.
Another neighbour and friend, Michael Carney, who had known Mr Rhodes for around 40 years, said he sat at his bedside while he was in the coma.
"My wife and my two girls went up there and were with him until he died, playing him music. He liked Queen and that," he said.
"He had no one. You can't have someone dying on their own."
Dozens of other people were injured, including nationals of Britain, France, Romania, South Korea, Greece, Germany, Poland, Ireland, China, Italy and the US.
On Thursday evening, Londoners came together in Trafalgar Square for a candlelit vigil to show defiance and solidarity.
London Mayor Sadiq Khan told the packed square: "Those evil and twisted individuals who tried to destroy our shared way of life will never succeed and we condemn them.
"When Londoners face adversity we always pull together. We stand up for our values and show the world we are the greatest city in the world."