A spokesman for the Metropolitan Police said:
We are urgently trying to contact the complainant so we can discuss with her the issues that she is raising on social network sites, to once again explain our approach and tactics in this investigation to provide both answers for her and clarity.
A huge amount of evidence, including hundreds of tweets, has been captured by officers and thoroughly examined. This has been a complex and large investigation that has involved the examination of hundreds of messages sent on Twitter.
A number of people have so far been arrested in connection with the complaint, and remain on bail.
The MPS has worked closely with the CPS to ensure that what we are examining and highlighting for prosecution meets a criminal threshold. Officers have been in ongoing dialogue with the complainant since the investigation started. We are mindful of the truly hurtful and distressing impact that receiving such communication can have, however we must be sure to focus our efforts on the things that we and the CPS believe is a crime and can be prosecuted.
Caroline Criado-Perez said:
It's just appalling. I got an email saying 'why don't you go through what you've had' from three users with certain handles. It just shows such insensitivity to someone who's been through so much, I can't believe it. I've spent the afternoon crying just from the sheer awfulness of it.
They wanted me to go through all the Tweets again because of their incompetence. Every time I have to go through it it's reliving it all over again.
A feminist campaigner who was sent a barrage of abusive messages on Twitter, has claimed that police lost evidence that she handed to them.
Caroline Criado-Perez, from north London, was one of a number of women who received deaths threats - and threats of sexual abuse - on the social networking site, after campaigning to have a woman's picture printed on a new banknote.
She says that the police appear to have lost supporting evidence that she had emailed to them.
Journalist Caroline Criado-Perez has told ITV London that although she welcomes Twitter's new move to report abusive messages, there was more that needed to be done.
The social networking site Twitter has introduced a new way to report abusive messages after several London women were victims of trolling.
The online company came under fire after journalist Caroline Criado Perez received violent and threatening 'tweets'.
Lucrezia Millarini reports:
Kim Graham, who started the Change.org petition for Twitter to do more to protect its users, has welcomed the site's move to add a "report tweet" option for users who are sent abusive messages.
I'm thrilled that Twitter has started making progress on this.
Online bullying and harassment has been too common for too long, and this is a very welcome first step toward online safety for women.
There are always improvements that can be made, but this proves that if we speak up together we can really have an impact.
Caroline Criado Perez said it was "great" that Twitter had taken a "first step" in dealing with harassment on the social media site, but said more needed to be done.
Ms Criado Perez, from north London, was one of a number of women who were subjected to a torrent of abuse by Twitter users last month.
Ms Criado Perez said: "It's great that Twitter has listened.
"There are still issues: users have to agree for the report to be potentially shared with the harasser, and there are some boxes that could be auto-populated that aren't. But overall, this is a fantastic first step."
Twitter has launched a "report tweet" feature aimed at helping people who receive abusive messages.
A number of womern were recently targeted on the site, including Walthamstow MP Stella Creasy. Over one hundred thousand people signed a petition to get the site to improve its procedures for dealing with abuse.
Life in Victorian London during Jack the Ripper's 'Autumn of Terror' is brought to life on Twitter.
Thank you for following the Whitechapel Real Time campaign. Welcome to Victorian London, 1888…
Jack the Ripper historians are pooling their knowledge into a Twitter feed which launched today.
They hope to show what Twitter might have looked like if it was around when the notorious killer stalked the streets of Whitechapel, 125 years ago.
It will include tweets from imagined detectives, reporters and local workers.
The project can be followed @WChapelRealTime