TUCSON, Arizona (Reuters) – Accused Tucson shooter Jared Loughner will face several more charges after he is tried in federal court for the attempted assassination of Rep. Gabriel Giffords and attempted murder of two of her aides, prosecutors said on Friday.

The 22-year-old college dropout is accused of opening fire on a crowd of bystanders outside a Giffords event at a grocery store on January 8, killing six people and wounding 13.

On January 24, he pleaded not guilty to federal charges of attempting to assassinate Giffords and attempting to murder two of her staff members in the shooting spree that occurred in Arizona's Pima County, which surrounds Tucson.

In a joint statement released on Friday, U.S. Attorney Dennis K. Burke and Pima County Attorney Barbara LaWall said that they could not proceed with state and local charges against Loughner until the federal case is complete.

"As required by the statute, once those charges have been fully prosecuted through the federal court system, Arizona state charges will be prosecuted by the Pima County Attorney's Office," the statement said.

"These cases will be tried in sequence and will ensure that all rights of the victims and their families are vindicated," it added.

In addition to the charges for the attempted murder of Giffords and her aides, federal charges are expected to be filed for the murders of federal judge John Roll and Giffords' aide Gabe Zimmerman.

After that, Loughren could be charged by Pima County with all six murders -- even if he has been convicted already of murdering Roll and Zimmerman -- as well as for aggravated assault, attempted murder and endangerment, Lawall said.

"There could be considerable delay and that makes me distraught for the victims who are going to have to wait for justice," Lawall told Reuters.

Giffords was shot through the head but survived, and is currently undergoing intensive rehabilitation in Texas.

The shooting rampage reignited a national debate about gun control and triggered soul searching about whether vitriol in U.S. politics had encouraged violence against elected officials -- although motives for the attack remain unclear.

In a separate development, prosecutors asked Judge Larry Burns to order Loughner to submit hand-writing samples for possible evidence at the trial.

The samples are sought to see if they match "handwritten references to the Member of Congress the defendant is accused of attempting to assassinate, as well as references to guns and bullets" found at his home, prosecutors said in documents lodged at the court.

Investigators have said they found an envelope at Loughner's home with hand-written phrases that said "I planned ahead" and "My assassination." The name "Giffords" also was found and what appeared to be Loughner's signature.

Additional notebooks with Loughner's handwriting also were found, prosecutors said.

Loughner could face up to life in prison for trying to kill the lawmaker and the other two attempted murder charges carry a maximum sentence of 20 years.

(Reporting by Tim Gaynor and David Schwartz; editing by Greg McCune)

HAVANA (Reuters) – Cuban prosecutors will seek a 20-year prison sentence for U.S. aid contractor Alan Gross, accused of crimes against the state, Communist Party newspaper Granma said on Friday, in a case that has stalled progress in U.S.-Cuba relations.

A government statement posted on the paper's website said Gross was accused of "Acts Against the Independence and Territorial Integrity of the State" and that a trial date for him would be set soon.

Gross, 61, has been detained since he was arrested at his Havana hotel in December 2009.

Cuban authorities have accused him in the past of illegally importing satellite communications equipment and possibly spying.

The government statement gave no details about the charge, but the Cuban law it referred to said that someone "who in the interest of a foreign state" commits an act detrimental to the independence of the Cuban state or its "territorial integrity" faces a jail sentence of 10 to 20 years or the death penalty.

The United States has said Gross was only providing satellite communications equipment and Internet access for Jewish groups in Cuba and was not a spy.

The Obama administration said in a statement that "instead of releasing Mr. Gross so he can come home to his wife and family, today's decision by Cuban authorities compounds the injustice suffered by a man helping to increase the free flow of information, to, from, and among the Cuban people."

Representative Ileana Ros-Lehtinen, the Florida Republican who chairs the U.S. House Foreign Affairs Committee, said the news was "yet another wakeup call that the United States cannot negotiate with ruthless dictators."

Gross was working in a U.S. program begun by the Bush administration aimed at promoting political change in Cuba, which the Cuban government views as part of a long-standing U.S. attempt to topple the communist-led island's leaders.

Gross' attorney, Peter Kahn, in Washington said it was a "positive development" the case was moving forward, but the charges were the product of U.S.-Cuba hostility that dates to Cuba's 1959 revolution.

They "demonstrate once again that Alan is caught in the middle of a long-standing political dispute between the United States and Cuba," he said in a statement.

"Each time Alan traveled to Havana he declared everything that was required by Cuban customs authorities. Never did the Cuban authorities raise concerns about what he brought with him," Kahn said.

"Neither his presence nor actions in Cuba were ever meant to, or in fact did, pose any threat to the Cuban government," he said, calling on the two governments to resolve the case through diplomatic channels.

HURDLE TO CLOSER TIES

The United States has previously demanded his release and said there would be no major initiatives in U.S.-Cuba relations until he was free.

His detention has become a serious obstacle between the two nations, stalling steps by the governments of U.S. President Barack Obama and Cuban President Raul Castro to improve ties.

Ros-Lehtinen repeated criticism of Obama administration moves last month that further relaxed restrictions on U.S. travel and remittances to Cuba.

"This Administration's insistence on continually reaching out to the Cuban tyranny and seeking to ease restrictions is rewarding the despotic Castro brothers while at the same time undermining U.S. interests and security," she said in her statement.

Friday's announcement followed some recent positive signals the Gross case may be coming to some kind of resolution.

Last month, a senior U.S. State Department official expressed cautious optimism that Gross would be tried and freed once formal charges had been pressed.

A Western diplomat in Havana said at the time the trial would likely take place in a few weeks and that Gross was expected to plead guilty, then be sent back to the United States.

It was possible, said Cuba expert Arturo Lopez Levy of the University of Denver, that the charges would set the stage for a "humanitarian gesture" by Cuba.

Gross' wife, Judy, visited her husband last summer and told Reuters in October she had written a letter to Raul Castro expressing the couple's remorse for his work in Cuba.

She has pleaded with Cuba to release Gross because their daughter is being treated for breast cancer, but there has been no public reply by the government.

Gross, who is being held in a cell at a military hospital, is said to have lost 90 pounds (41 kg) in jail and suffers from health problems.

(Additional reporting by Esteban Israel; Editing by Eric Beech)

LOS ANGELES (Reuters) – Upscale burrito chain Chipotle Mexican Grill Inc faces a wider probe of its hiring by immigration officials, after the company came under scrutiny in Minnesota and had to fire workers.

Chipotle has received U.S. Immigration and Customs Enforcement (ICE) "notices of inspection" for restaurants in Washington, D.C., and Virginia, co-Chief Executive Monty Moran told Reuters on Friday.

The new notices follow ICE inspections of the restaurant chain's Minnesota employees. Labor leaders say as many as 700 Chipotle workers were subsequently fired after their eligibility for legal employment in the United States could not be verified.

The company, which operates more than 1,000 restaurants, mostly in the United States, declined to say how many Minnesota workers were fired.

"Because this is an ongoing issue with ICE, we are not disclosing details like that," Moran told Reuters in an email.

"We have always taken this issue very seriously, and over the last five years we have done a great deal to improve our systems and our document review capabilities and procedures," Moran said.

"Certainly this incident has been eye-opening for us and caused us to redouble our efforts to make sure we are doing all we can short of running afoul of the mandate of the Department of Justice."

Chipotle, a Wall Street darling whose shares have gone from under $40 to over $240 in just over two years, is one of the highest-profile companies to come under ICE scrutiny in what experts call a crackdown on employers.

Under President Barack Obama, immigration enforcement strategy has shifted to finding evidence to criminally charge or fine employers. ICE previously conducted large-scale raids that netted large numbers of employees, many from Mexico and Central America.

Chipotle is one of just a handful of publicly traded restaurant companies that own and operate all of their outlets. Rivals like McDonald's Corp and KFC and Taco Bell owner Yum Brands Inc are highly franchised, and responsibility for hiring often falls to independent restaurant operators.

ICE spokeswoman Gillian Brigham told Reuters in an interview earlier this week: "Our inspections are not random. All of our work site cases and ... audits are based on leads and intelligence. So we are not picking businesses out of a hat."

Obama backs sweeping immigration reform, and his reelection might depend on Hispanic voters who give great importance to overhauling policy to deal with some 12 million undocumented immigrants.

Shares in Chipotle, which plans to open as many as 145 restaurants in 2011, rose 3 percent, or $7.09, to close at $246.31 on the New York Stock Exchange.

(Additional reporting by Ed Stoddard in Dallas; editing by John Wallace, Gary Hill)