British police said Thursday that they had charged a North African man with the murder of a senior police officer during a raid that was part of a nationwide investigation into terrorism.
They said the 27-year-old man, who was not identified, had also been charged with four counts of attempted murder after the raid on a Manchester apartment.
Police raided the apartment Tuesday, arrested three men and held them for about an hour before one of them broke free, grabbed a knife and stabbed Det. Stephen Oake in the chest.
The detained man also injured four other officers before being brought under control.
Oake, a 40-year-old father of three, died later in a hospital.
Media reports have linked the three raid suspects and a 32-year-old Algerian who turned himself in Wednesday to the discovery of traces of the deadly poison ricin during a raid on an apartment in London last week.
In Washington, a senior Bush administration official said the United States is investigating whether some men arrested in England with traces of ricin are linked to an Islamic extremist group in northern Iraq that has experimented with the poison.
The official, speaking on the condition of anonymity, said U.S. intelligence has indications of connections between the group of Algerians in Britain and Ansar al-Islam, a Kurdish group that U.S. counterterrorism officials have said has ties to Al Qaeda.
Several U.S. counterterrorism officials said that they have not established any definitive link and that they have no evidence connecting either to the government of Iraqi President Saddam Hussein.
Last year, Ansar al-Islam experimented with ricin and potential biological weapons, but U.S. officials do not believe the efforts were very sophisticated.
Since Jan. 5, British authorities have arrested several Algerians on suspicion of terrorism. At one of their apartments, police discovered the traces of ricin.