Surrey Police's massive manhunt for Abigail Witchalls' attacker turned up two suspects within two days of the crime.
A 28-year-old man and 29-year-old woman were arrested after they went voluntarily to Leatherhead police station but were later released and eliminated from the inquiry.
Detectives focused their attention on 32 possible suspects and warned that it could take weeks to discover if any of those were the attacker.
As the investigation shifted towards complex forensics work, experts examining the buggy in which Mrs Witchalls had been pushing her 21-month-old son, Joseph, moments before the attack thatleft her paralysed. They also began putting questions to Abigail, who was able to communicate through blinks and facial movements. Collecting material from the lane in Little Bookham, officers seized 468 exhibits, many of which have now been sent for tests, including "magnifying" traces of DNA.
Detective Superintendent Adrian Harper, who is leading the investigation, said: "It can take either days or weeks, depending on whether the exhibit is straightforward fingerprints or low-profile DNA."
On 25 April, although unable to talk, Mrs Witchalls mouthed a statement to police from her hospital bed. The next day, she described the attacker and her ordeal to officers using the same method of communication.
Two days later a further arrest was made - a 25-year-old Surrey man - but he was released. Then, on 11 May, officers reveal that one of the suspects in the case died after taking a suspected paracetamol overdose. Richard Cazaly, 23, drove to Scotland three days after the attack and took the tablets. He was admitted to hospital in Inverness on 28 April and later that day transferred to the Edinburgh Royal Infirmary where he died on 30 April.
Cazaly, from Hampshire, had been living on Water Lane, Little Bookham, and had similarities to the description given by Mrs Witchalls. Surrey Police believe they have evidence linking Cazaly to the attack.