A federal jury has begun deliberating the immigrant-smuggling case against US poultry giant Tyson Foods.

A Tyson attorney said in a closing statement that the poultry producer and three of its managers tried to follow immigration law with a voluntary employment screening programme endorsed by the government.

Tom Green, an attorney for the Arkansas-based company told the court that US immigration laws allow a company to hire a “refugee from the North Pole or the man from Mars” if the worker has identity documents that look genuine, reported the Association Press.

Assistant US Attorney John MacCoon had claimed earlier that Tyson’s top executives had known that illegal workers were being hired at the company’s poultry plant.

US District Judge Allan Edgar has dismissed some of the charges against Tyson since the trial began, but charges of conspiracy, transporting illegal immigrants and fraudulent documents still remain.

Six managers were charged along with Tyson in December 2001. One manager fatally shot himself a few months later, while two others made plea bargains in January and testified for the government.

The highest-ranking current Tyson official on trial is Robert Hash, 50, a regional vice president who faces seven charges, including two of conspiracy.

Plant manager Keith Snyder, 44, faces a single conspiracy charge.

Retired division human resources manager Gerald Lankford, 64, faces charges of conspiring to violate immigration laws and obstructing their enforcement.

If found guilty, the managers face prison sentences and fines, while Tyson itself could face millions of dollars in fines.