Half of police officers facing gross misconduct investigations in the last two years resigned or retired before their cases were heard, figures show.
A total of 833 officers were added to the Disapproved Register by forces in England and Wales in its first two years, the College of Policing said.
Of the 369 who left in the year between December 2014 and November 2015, 202 were dismissed, 147 resigned and 20 retired, while in the 12 months from December 2013, 215 were dismissed, 219 resigned and 30 retired.
The numbers of officers leaving before their cases were resolved, totalling 416 over the two-year period, comes despite Government steps to bar them from doing so in an amendment to police regulations, which came into effect in January 2015 but did not apply to ongoing investigations.
Among them were 34 officers accused of having a relationship with a vulnerable person, 11 who faced allegations of sexual conduct towards colleagues and 30 accused of domestic abuse.
Of the reasons for leaving the service over the two years, through dismissal, retiring or resigning, the highest number - 107 -did so because of a failure to perform their duty, followed by data misuse at 89 and giving false evidence at 74.
In 2014/15, eight officers were dismissed and three resigned while under investigation over child sex offences, taking the total for the 24-month period to 16.
The figures have been broken down by force for the first time, with the highest number, 148, leaving the country's largest force the Metropolitan Police, followed by the Ministry of Defence Police at 56 and Essex Police at 41.
The majority of those who were placed on the register were reported by colleagues, with internal complaints the source of 91% of cases in 2013/14 and 84% in 2014/15
The register was introduced to prevent officers from re-entering the service after being dismissed for misconduct or resigning or retiring while subject to a gross misconduct investigation where there would have been a case to answer.
College of Policing standards manager Detective Superintendent Ray Marley said: "There is a misconception that police do not report wrongdoing by their colleagues and this is clear evidence that they are confronting unacceptable behaviour and using formal misconduct mechanisms to hold their colleagues to account.
"The number of officers on the register represents a tiny percentage of the overall workforce which shows the level of misconduct across the service is low. However, the police are not complacent and will continue to report colleagues they believe have been involved in wrongdoing.
"The police have more than six million interactions a year with the public and confidence is rising. This is reflected by the Office for National Statistics which showed the proportion of adults who feel local police are doing a good or excellent job in 2013/14 was 63%, compared to a positive rating 10 years previously of 47%."
The figures were also broken down by rank and showed the number of police constables who left due to misconduct was 697, while there were 92 sergeants, 39 inspectors, nine chief inspectors, three superintendents and three chief superintendents.
All 43 forces in England and Wales, along with British Transport Police and the Ministry of Defence Police, voluntarily contribute to the register.
Essex Police deputy chief constable Matthew Horne said: "We must maintain public confidence by maintaining the highest of standards. Every day in Essex officers do some amazing things, but sometimes they will get things wrong and make mistakes.
"The fact that the many of these cases are raised, investigated and adjudicated by Essex Police is something that the people of the county can take as firm evidence of the force's commitment to ensuring they get the police service they have every right to expect."