Prosecutors and defence lawyers rested their cases Wednesday without any testimony from O.J. Simpson, who's charged with kidnapping and armed robbery. (Ethan Miller/Associated Press)

The judge and lawyers for both sides in the O.J. Simpson kidnapping and armed robbery case met behind closed doors in Las Vegas Thursday to work on instructions to the jury, which they plan to present before closing arguments later in the day.

Simpson, 61, and co-defendant Clarence (C.J.) Stewart, 54, have pleaded not guilty to 12 charges, including kidnapping, armed robbery and conspiracy.

They are accused of robbing and holding two sports memorabilia dealers at gunpoint a year ago to get back mementos that once belonged to the former NFL star.

Neither accused testified at the trial before their lawyers rested their cases Wednesday.

Each man could face anywhere from five years to life in prison if convicted.

"I feel there will be a hung jury," star prosecution witness Thomas Riccio said after both prosecutors and defence lawyers rested their cases.

Riccio is the collectibles broker who arranged the confrontation between Simpson and the sports memorabilia dealers at a Las Vegas hotel in September 2007.

"If you ask 12 people, half will say he's guilty and half will say he's not guilty," said Riccio, whose secret audio recordings of Simpson before, during and after the hotel room confrontation were key evidence for the prosecution.

Clark County District Court Judge Jackie Glass told the jury of nine women and three men they could begin deliberations as early as Thursday, after she provides instructions on the law and both sides make closing arguments.

Simpson was acquitted in 1995 in Los Angeles of charges that he murdered his ex-wife, Nicole Brown Simpson, and her friend Ronald Goldman. He was later found liable for the deaths in a civil case.

With files from the Associated Press