BAGHDAD — Iraqi authorities want the U.S. government to sever all contracts in Iraq with Blackwater USA within six months and pay $8 million in compensation to each of the families of 17 people killed when the firm's guards sprayed a traffic circle with heavy machine gun fire last month.

The demands — part of an Iraqi government report examined by The Associated Press — also called on U.S. authorities to hand over the Blackwater security agents involved in the Sept. 16 shootings to face possible trial in Iraqi courts.

The tone of the Iraqi report appears to signal further strains between the government of Prime Minister Nouri al-Maliki and the White House over the deaths in Nisoor Square — which have prompted a series of U.S. and Iraqi probes and raised questions over the use of private security contractors to guard U.S. diplomats and other officials.

Al-Maliki ordered the investigation by his defense minister and other top security and police officials on Sept. 22. The findings — which were translated from Arabic by AP — mark the most definitive Iraqi positions and contentions about the shootings last month.

The report also highlights the differences in death tolls and accounts that have complicated efforts to piece together the chain of events as one Blackwater-protected convoy raced back toward Baghdad's Green Zone after a nearby bombing, while a second back-up team in four gun trucks sped into the square as a back-up team.

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British premier says troops will be cut to 2,500 in Iraq

LONDON — Britain will halve its remaining troop contingent in Iraq next spring, Prime Minister Gordon Brown announced Monday. A British official later said they could not guarantee that any troops would remain in Iraq by the end of 2008.

Brown, under fire over his decision not to call an election for this year, said Britain would lower troop levels to 2,500 by mid-2008 and redeploy logistics staff to neighboring states. The British leader was clearly hoping the announcement would help boost his popularity among a public weary of the war.

Aides had stoked election rumors for weeks, particularly as lawmakers and activists gathered for a series of political party conferences. But Brown scrapped the plans Saturday as opinion polls suggested his early wave of public support had waned.

Brown told lawmakers Monday his Iraq plan follows the success of the U.S. troop increase this summer and efforts by Iraqis to drive suspected al-Qaida militants from havens in Anbar province, west of Baghdad.

He said decisions on further cuts would be made once the reduction to 2,500 was complete, rejecting a call from opposition lawmakers to set a timetable to withdraw all British forces.

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U.S. explored potential for using radioactive poisons

WASHINGTON — In one of the longest-held secrets of the Cold War, the U.S. Army explored the potential for using radioactive poisons to assassinate "important individuals" such as military or civilian leaders, according to newly declassified documents obtained by The Associated Press.

Approved at the highest levels of the Army in 1948, the effort was a well-hidden part of the military's pursuit of a "new concept of warfare" using radioactive materials from atomic bombmaking to contaminate swaths of enemy land or to target military bases, factories or troop formations.

Military historians who have researched the broader radiological warfare program said in interviews that they had never before seen evidence that it included pursuit of an assassination weapon. Targeting public figures in such attacks is not unheard of; just last year an unknown assailant used a tiny amount of radioactive polonium-210 to kill Kremlin critic Alexander Litvinenko in London.

No targeted individuals are mentioned in references to the assassination weapon in the government documents declassified in response to a Freedom of Information Act request filed by the AP in 1995.

The decades-old records were released recently to the AP, heavily censored by the government to remove specifics about radiological warfare agents and other details. The censorship reflects concern that the potential for using radioactive poisons as a weapon is more than a historic footnote; it is believed to be sought by present-day terrorists bent on attacking U.S. targets.

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Off-duty deputy fired 30 rounds into Wisconsin home

CRANDON, Wis. — An off-duty sheriff's deputy who killed six young people fired 30 rounds of ammunition after he burst into a home where friends had gathered, investigators said Monday.

Tyler Peterson, 20, who later died after exchanging gunfire with law enforcement officers, had been in a relationship with one of the victims, authorities said at a news conference.

"They were in a relationship for a few years," said Police Chief John Dennee. "They had broken up and gone back and forth."

The rampage raised questions among residents of the remote northern Wisconsin community about how Peterson could have met requirements to become a law enforcement officer. No psychological testing was performed, but he had undergone other background checks and completed all required training by the state, authorities said.

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Obama touts lowering U.S. greenhouse gas emissions

PORTSMOUTH, N.H. — Democrat Barack Obama is calling for sharply reducing U.S. greenhouse gas emissions and forcing power companies and other businesses to pay for all of their pollution.

He said Monday that he would get results, unlike those whom he said are bound by the unwritten rules and timidity of Washington politics.

"Our energy problem has become an energy crisis because no matter how well-intentioned the promise, no matter how bold the proposal, they all fall victim to the same Washington politics," Obama said.

He spoke at the new, energy-efficient Portsmouth Public Library, where about 100 invited guests watched a short video featuring every president since Gerald Ford promising to curb the use of fossil fuels — contrasted with a graphic illustrating the nation's increasing dependence on foreign oil. Obama suggested his rivals for the Democratic nomination would provide more of the same.

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Doctor prescribed 'excessive' steroids to pro wrestler Chris Benoit

ATLANTA — The amount of testosterone prescribed to pro wrestler Chris Benoit far exceeded the normal amount for a hormone disorder he was purportedly being treated for, federal prosecutors said in new court papers.

The papers were filed in a criminal case against Dr. Phil Astin, Benoit's personal physician, who is charged with overprescribing medication to two other patients.

More charges against Astin are expected.

Authorities said Benoit, 40, strangled his wife with a cord, used a choke hold to strangle his 7-year-old son, placed Bibles next to the bodies and hanged himself on a piece of exercise equipment the weekend of June 22 in their suburban Atlanta home.

Steroid use has lingered as a theory behind the killings, since anabolic steroids were found in Benoit's home and tests conducted by authorities showed Benoit had roughly 10 times the normal level of testosterone in his system when he died.

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Studies find that blood put in storage lacks nitric oxide

WASHINGTON — Much of the stored blood given to millions of people every year may lack a component vital for it to deliver oxygen to the tissues. Nitric oxide, which helps keep blood vessels open, begins breaking down as soon as blood goes into storage, two research teams report in separate studies in this week's online edition of Proceedings of the National Academy of Sciences.

In recent years, doctors have become increasingly concerned about levels of heart attack and stroke in patients receiving transfusions and the new findings may help explain that.

"It doesn't matter how much oxygen is being carried by red blood cells, it cannot get to the tissues that need it without nitric oxide," said Dr. Jonathan Stamler of Duke University, leader of one of the research groups.

Blood vessels relax and constrict to regulate blood flow and nitric oxide opens up blood vessels, allowing red blood cells to deliver oxygen, he explained.

"If the blood vessels cannot open, the red blood cells back up in the vessel and tissues go without oxygen. The result can be a heart attack or even death," he said.

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Sprint Nextel CEO Gary Forsee steps down

NEW YORK — Sprint Nextel Corp. Chairman and CEO Gary Forsee resigned Monday as the company's board expressed disappointment with the financial results of the nation's third-largest wireless provider. Sprint also lowered its financial forecast for the current quarter.

"It is the right time to put in place new leadership to move the company forward in improving its performance and realizing corporate objectives," board member Irvine Hockaday said in a company statement.

The board said it was searching for a replacement for Forsee, who was also president. In the meantime, Director James Hance Jr. will assume the role of acting nonexecutive chairman, and Chief Financial Officer Paul Saleh will serve as acting CEO.

Also Monday, Sprint Nextel said it expects to report a net loss of approximately 337,000 monthly subscribers in the third quarter. Its operating income excluding some items is expected to fall below the previously forecast range $11 billion to $11.5 billion. Revenue is expected to fall below the earlier forecast of $41 billion to $42 billion.

Sprint Nextel shares closed Monday at $18.50, down 51 cents or 2.7 percent. In extended trading, after the announcement of Forsee's departure, the shares gained 11 cents.

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Sex abuse settlement renews scrutiny of Catholic prep schools

SANTA ANA, Calif. — Bishop Tod D. Brown was lauded three years ago for quickly handling Orange County's share of the nationwide church abuse scandal, reaching settlements totaling $100 million for some 90 victims.

But a source of nearly a fifth of those cases — two prestigious parochial high schools — continues to haunt the diocese and has now exposed Brown to old allegations of child abuse and the possibility of being held in contempt of court this week.

The Roman Catholic Diocese of Orange settled four more lawsuits Friday for just shy of $7 million. Three were filed by former students at Mater Dei and Santa Margarita high schools who said lay teachers sexually abused them.