Paul Evans generated both outside cheer and inside concern during his time as police commissioner for the north-eastern US city of Boston.
The man who will now head the UK's Police Standards Unit presided over a dramatic drop in violent crime and a new era of partnership with community organisations.
Mayor Menino (left) said Mr Evans' legacy would be strong in Boston
But he also clashed with the trade unions of his own officers as he sought to implement reforms.
Mr Evans was appointed acting commissioner in 1993 and given the permanent post the following year at a time when the Boston police force was under constant criticism for failing to do its job.
During Mr Evans' 10 years in the job - one of the longest tenures of an urban police chief in the US - drops were recorded in most areas of crime.
Since 1985, violent crime in the city fell by 34%, homicides were down by 68% and there were 40% fewer burglaries.
In 2002, the overall crime rate was at a 31-year low.
Mr Evans spent much time establishing relationships in neighbourhoods where the police were seen as anything but friends.
He managed to overcome potentially disastrous events - such as a drug raid on the wrong house which led to the death of a black minister - and still have the confidence of community leaders.
Reba Danastorg, executive director of the Boston Ten Point Coalition, said Mr Evans' departure would be a huge loss to the city.
She praised Mr Evans for working with community groups such as her faith-based organisation to tackle crime particularly among black and Latino youths who could be drawn into violence or drugs.
"He is a superb guy to have around," she told BBC News Online.
She praised him for looking beyond simply the uniformed officers to involve the community - even though groups such as hers were once sceptical of a police force seen as tainted.
"He looks for what works best, not what has worked in the past. He is very quick to understand that today we are not where we were yesterday... he will do well wherever he goes."
UK Home Secretary David Blunkett said Mr Evans key task as director of the Police Standards Unit will be to raise standards across the nation's police forces.
And it is instituting reform among his city's officers themselves that brought him problems.
The leader of the Boston Police Patrolmen's Association, Thomas Nee, told the Boston Globe newspaper that Mr Evans did a better job of selling himself to the public than to his own officers who were uncertain that they would have his support.
The union even passed a no-confidence vote in Mr Evans last year when he wanted to ban officers shooting at moving cars following the death of a woman passenger.
But Mayor Thomas Menino said Mr Evans would leave a great legacy in Boston and the Boston Globe said in an editorial that he "understands the demands of urban policing better than any commissioner in the United States".