A FOURTH man questioned about Wednesday night's killing of PC Patrick

Dunne was released on bail last night pending further inquiries, New

Scotland Yard said.

The man, not named, arrested in the early hours of Thursday while

driving north towards Leicester, was granted police bail until November

24.

But the man was rearrested immediately on behalf of West Midlands

Police, who want to interview him about an unrelated matter and are due

to collect him this morning.

Earlier yesterday, three other men, a Jamaican and two others born in

Britain, were released on police bail for a month after being arrested

in connection with murders of PC Dunne, 44, and William Danso, 31, in

Clapham, south west London.

New Scotland Yard said the man granted bail last night was first

detained by local police for an alleged traffic offence and was found to

be carrying a 9mm automatic handgun. Forensic tests were carried out on

the weapon.

The murders of PC Dunne and Mr Danso, and another fatal shooting on

Thursday in broad daylight in the busy Uxbridge Road in Shepherd's Bush,

west London, have heightened fears that well-armed drug gangs are

growing more violent and ruthless.

A post-mortem was carried out yesterday on the Shepherd's Bush victim,

identified as Mr Anthony Melhado, 29, of White City, west London.

Metropolitan Police Commissioner Paul Condon warned that vicious

gangsters were locked in a brutal struggle for control of the capital's

crack-cocaine trade. Mr Condon said these well-armed and ''desperate''

criminals were prepared to shoot ''indiscriminately'' in their ''turf

war'' over sales of crack.

Mr Condon also disclosed that a major operation was under way against

crack gangs in south London, where there have already been four

drugs-related murders this year.

PC Dunne had been advising a couple over a dispute with a third person

in Clapham on Wednesday night when he heard shots from across the road

and went to investigate. He confronted an armed gang and is believed to

have been shot from a distance of about 30 feet as he reached for his

radio. He died instantly.

Mr Danso, a Ghanaian working as a bouncer at local clubs and pop

concerts also was found dead at the scene from gunshot wounds. Police

found cannabis worth a few thousand pounds hidden in a box in the back

garden of Mr Danso's ground-floor flat and there is speculation that his

murder was a ''punishment'' prompted by a row over a drugs deal.

Meanwhile, senior detectives were stung by criticism that they had

misjudged the extent of the crack problem in south London when

disbanding their specialist intelligence unit and Operation Dalehouse.