The links are close, and not always healthy. The recent furore that broke over the Mail on Sunday's fresh revelations concerning Colin Stagg is a case in point. The story was written by a former senior police press officer at Scotland Yard.
As forms of media have multiplied, so police media strategies have been adapted to the trends. The former chief constable of Devon and Cornwall, John Alderson, describes how the police and the public used to meet face to face in the street and the marketplace.
"Now the police and many of the public travel in cars and there is not the same direct contact," he says. "The marketplace is now the media and the police must play a role in that arena." Alderson believes that it is impossible to be a good chief constable and not be media-savvy.
The variety of media to which the police has access has expanded radically, with programmes such as Crimewatch and Crime Monthly offering immediate dramatic contact with millions of people. The average audience for Crimewatch is nine million. Since its launch in 1984 there have been 122 programmes, featuring 1,510 cases. The police have made 451 arrests as a direct result of the programme, leading to 296 convictions, says the BBC.
But are the uses made by the police of the media altogether benign? There is growing concern among some journalists that programmes such as Crimewatch can in fact perpetrate injustice, despite all the hype about cases being solved through the intercession of viewers.
Danny Penman, for one, a former Independent journalist and freelance writer, fears the influence of such programmes. "You could easily get a situation where people make up events or that encourages people to come forward who don't really have solid information," he says.
This may have been a factor in the case of Frank Marnell, who was wrongly accused of murder. Crimewatch's producers mounted a reconstruction of the crime and broadcast an artist's impression. As a result, viewers identified Marnell as a suspect. It was not until the committal stage that he was finally cleared, after individuals came forward to say that he had been with them at the time of the murder. Marnell suffered from a mental condition, so was particularly vulnerable.
The police also play an increasing role in fictional cop programmes. John Alderson is a consultant on The Chief and helped to devise the programme. The Bill is in regular contact with the Metropolitan Police, and there are police consultants on most television cop programmes. A company called Cops on the Box provides advice, expertise and personnel, for a price, to television producers.
John Deal, secretary of the Association of Chief Police Officers Media Advisory Group, emphasises that the role of the police media service is to inform the public in an open and accountable way. Alderson stresses that it would be wrong "to exploit the media to misinform".
Consider the case of the recent shooting of the IRA suspect Diarmuid O'Neill. In the initial reports on the case, a number of national papers referred to an IRA man being killed in a shoot-out with police. It was only the next day - after the initial and lasting image had already been created - that there was an admission that O'Neill had been unarmed when shot.
Cases of deaths in custody show most clearly the police handling of the media. Raju Bhatt, a solicitor at Birnbergs, says: "As soon as a death occurs the police media spin doctors come into play.
"Time and time again, heart disease is given as a provisional view of the cause of death. The implication is that the individual died of natural causes."
Take the case of Wayne Douglas, who died in custody after being arrested and taken to Brixton police station in December last year. The cause of death was given as "a defective heart".
On the day of the death the Metropolitan Press Bureau stated that: "To protect themselves officers used long batons to disarm him of the large kitchen knife he was carrying". However, by the time the Police Complaints Authority - which investigates all such deaths - issued their first press release, the batons had disappeared.
"At 2.30am the occupier called the police who chased and arrested a man at a playground half a mile away. It is claimed that officers were threatened with knives during the arrest," the PCA release said. The sudden disappearance of the long batons in the official record proved to be crucial to the spin given by media relations officers in the aftermath of the riot in Brixton that followed Douglas's death.
In the acres of newsprint the riot generated, the role of the batons, and in fact the whole issue of death in custody, were largely overshadowed by a focus on "thugs and criminals" and inner-city deprivation.
The police media then went on the offensive, accusing speakers at a public meeting outside Brixton police station of incitement to riot. Lawyer Rudy Narayan and the National Black Caucus co-ordinator Lee Jasper were singled out for particular attention.
The success of this offensive was evident on the front pages of the newspapers of Friday, 15 December.
"Police target riot speakers" as "incitement charges considered" said The Guardian. "Scotland Yard chief reveals how activists planned to target his officers and orders criminal inquiry into incitement to violence," wrote the Daily Mail.
Helen Shah, co-director of Inquest, the human rights non-governmental organisation, depicts the media police operation as "an irresponsible disinformation campaign".
Journalists' views on police media operations vary. A noted crime correspondent said that the situation now is much better than it was, say, 10 or 15 years ago, when crime correspondents used to work from Scotland Yard. Relations are now far more open and above board, he claims.
But for Danny Penman, the police play a mainly obstructive role. "The police basically see journalists as getting in the way and don't see any need to be answerable to the public. The only thing you can rely on the police for, in my experience, is arrest numbers," he says.
Supporters say that the police media services have become more open and accessible to the public.
Some recent troubling cases suggest that the contrary is the case: far from informing an ever more demanding public, police media operations are too often exercises in propagandan