The prime suspect in the stabbing of Abigail Witchalls would have been charged if he had not killed himself, police announced yesterday.

Richard Cazaly, 23, told his girlfriend he feared there was a "monster" inside him. In a suicide note he wrote: "I don't remember what happened but I'm scared I did it."

The pregnant Mrs Witchalls, 26, was left paralysed after being stabbed in the neck as she pushed a buggy with her 21-month-old son, Joseph, in a country lane near her Surrey home in on April 20.

Despite some contradicting evidence, Assistant Chief Constable Mark Rowley said yesterday: "The case is solved All the available evidence points to Richard Cazaly being the offender."

The drifter's long-term drug abuse, coupled with a bottle of vodka he drank on the morning of the attack, a may have caused him to become "psychotic and violent", Mr Rowley added.

Cazaly interviewed twice

Police spoke to Cazaly twice - once in a routine door-to-door inquiry and later in a random road block.

He only went from being regarded as possible witness to prime suspect when police learnt of his suicide a week after the attack.

Just a hedge separated Cazaly's workplace, a garden centre, from the narrow path Mrs Witchalls and Joseph took as they left their mother and toddler playgroup on that fateful afternoon.

She crossed on to Water Lane, the same road where Cazaly lived in a house share.

Yards further, on an unsurfaced section just before the lane enters the woods, her attacker drove slowly past them. The man left the car in the woods and started chasing them on foot.

Hunting in the woods

That day, as well as the day before, Cazaly did not go to work, claiming to have an upset stomach.

In truth he was hunting in the woods at the time of the attack, police said. He "persistently" lied to police, his friends and his girlfriend about that.

Yet no DNA evidence could place him at the crime scene and Mrs Witchalls could not pick him out of a photograph identity parade.

Her description of the knifeman's two looped silver earrings also mismatched the three-quarter-inch hole in Cazaly's one earlobe.

Still, she identified his blue Volvo 440 from 12 other cars as the one used by her attacker. Tyre tracks found nearby matched his own.

A specially trained police dog tracked Cazaly's scent from where the car was parked to the spot of the attack.

Whilst his friends said he was likeable man and that the attack would be "out of character", police found he heavily used cannabis and amphetamines. These can trigger psychotic behaviour linked to violent crime.

'I guess there is two of me'

On 25 April Cazaly drove to Scotland, where he took an overdose of paracetamol two days later. In his car detectives found a bag of knives and two suicide notes, including one they called an "implied confession".

The note to Vanessa MacKenzie, his Australian girlfriend who had just told him she was going home on an emergency ticket bought by her mother, read: "To my dearest Nessa. I am so, so sorry.

"I guess there is two of me. I am very scared but it will all be over soon and everybody will be better off.

"I don't remember what happened but I'm scared I did it. You deserve better.

"Your mum will look after you. Tell her I'm so sorry for all of this."

Photographs show a striking resemblance between Ms MacKenzie and Mrs Witchalls.

Up to £500,000 compensation

With their main suspect dead, Surrey Police took the unusual step of asking the Crime Prosecuting Services to say whether there was enough evidence to charge Cazaly if he had been alive.

Yesterday the CPS answered yes. But it warned: "This is in no sense a declaration that he was guilty." The decision would "merely have authorised the police to begin the legal process by charging him".

Mrs Witchalls gave birth to her second son, Dominic, last weekend. "She has carers to help her at home and is continuing to receive regular physiotherapy and occupational therapy," her family said in a statement.

They welcomed the end of the inquiry and offered their prayers to Cazaly's family.

She is set to receive a payout of up to £500,000 from the Criminal Injuries Compensation Authority to cover her living expenses and loss of earnings.