A man who was arrested over the stabbing of Abigail Witchalls has been released on police bail.
Mrs Witchalls was stabbed as she pushed her toddler son in a buggy
Mrs Witchalls, 26, is "stable" in intensive care after the attack in Little Bookham, Surrey, on Wednesday, which has left her paralysed.
The 28-year-old man had been arrested on suspicion of attempted murder along with a 29-year-old woman on Friday.
Earlier, the woman was released without charge and Surrey Police said she had been eliminated from the investigation.
The pair had been taken into custody after going into nearby Leatherhead police station on Friday afternoon. The man's blue Peugeot car was seized.
Police say they may try to interview Mrs Witchalls, although she can only communicate using blinks and facial expressions.
Detectives hope Mrs Witchalls may be able to give them key information to help to catch her attacker.
They said they would only talk to Mrs Witchalls if given permission by doctors, and any attempt to gain clues in this way would not take place immediately.
Martin Hollins choked back tears as he told of his pride in his daughter
A police spokesman said: "If we got the go-ahead from the hospital and she is able to communicate then we will at some point do that."
Earlier, Mrs Witchalls' father told of his "tremendous shock" at the attack.
Martin Hollins appealed for anyone with information on the stabbing to come forward.
Mrs Witchalls was stabbed in the neck as she pushed her toddler son Joseph in a buggy. Relatives are at her bedside at St George's Hospital in Tooting, south London, where her mother, Professor Sheila Hollins, also works.
Members of her family are caring for her son who is just under two years old.
He was found out of his buggy by his mother's side, as she lay slumped on the ground, by residents who came running after hearing screams.
Mrs Witchalls' husband Benoit, 26, has remained close to her bedside in hospital.
Mr Hollins said: "He's done a wonderful job of communicating with his wife and that's great to see.
"It's really hard, he's in such pain and I really feel for him," he added.