Victims Commissioner Louise Casey resigned today in order to head the Government's broad response to the riots, Prime Minister David Cameron announced.
Ms Casey quit after 18 months as Commissioner for Victims and Witnesses to head a new troubled families team in the Department for Communities and Local Government (DCLG).
In her resignation letter to Justice Secretary Kenneth Clarke, she said she had seen "a glimpse of some of the worst acts of human nature" and also "the very best of human behaviour".
Ms Casey will now "drive forward the Prime Minister's commitment to turn around the lives of 120,000 most troubled families", the Ministry of Justice said.
In her resignation letter, she said it had been an "enormous honour" to be the first Victims Commissioner, which was "one of the most challenging jobs that I have undertaken in terms of the very great suffering that I found, and the unmet need that is alongside it".
She said: "My team and I over the last 18 months have, however briefly, been shown a glimpse of some of the worst acts of human nature, the plight of those who have had loved ones taken from them and a response from the 'system' that, however well-meant, has often fallen short.
"I have also witnessed the very best of human behaviour - in those people who, after tragedy has hit them and their family, devote their lives to campaigning to make things better and supporting other people who are going through the same terrible experience.
"I have also seen first-hand how many victims act with courage and dignity despite awful personal circumstances, coupled with dealing with a system that does not always treat them as it should."
Ms Casey added that there was still much work to be done following her review into the needs of families bereaved by homicide.
Further consideration should also be given "to my calls for a 'victims' law' whereby, for the first time, there would be some statutory safeguard put in place for victims and witnesses", she said.
She added that she had not had time to address other concerns, including "the position of child victims of crime and their treatment as witnesses in the criminal justice system, and the lack of attention and care they receive when we ask them to bear witness for very serious crimes".