CHARLESTON, W.Va. (AP) - Closing arguments could come soon in the criminal trial of ex-Massey Energy CEO Don Blankenship, who's accused of putting profits ahead of safety in the years before a deadly coal mine explosion.

CHARLESTON, W.Va. (AP) Closing arguments could come soon in the criminal trial of ex-Massey Energy CEO Don Blankenship, who's accused of putting profits ahead of safety in the years before a deadly coal mine explosion.

The executive's attorneys rested their case Monday without calling a single witness on his behalf.

Though U.S. District Judge Irene Berger has not said exactly when closing arguments will be presented, the impending finish comes after the prosecution slogged through weeks of witness testimony and defense questioning. The government asserted that Blankenship chose dollars over human safety, with deadly results.

Blankenship could face up to 30 years in prison on charges of conspiring to break mine safety laws at Upper Big Branch Mine and lying to financial regulators and investors about company safety. The southern West Virginia mine exploded in 2010, killing 29 men.

Opting not to call any witnesses is a defense strategy that experts say is rare, aggressive and risky.

"It's a way of saying, 'The prosecution's case is so weak we don't need to respond, and we can win without calling a single witness,'" said Brandon Garrett, a University of Virginia law professor who wrote a book about corporate prosecutions.

It's unusual for the defense not to call witnesses who can "humanize the defendant," Garrett said.

The trial, which began Oct. 1, featured testimony from Massey management and miners, expert witnesses, federal regulators, and more.

Prosecutors painted Blankenship as a micromanager who received constant reports about Upper Big Branch, meddled in the smallest decisions at the mine and cared more about money than safety. His attorneys, meanwhile, used testimony from multiple prosecution witnesses to support his defense.

The judge dismissed jurors Monday and they were expected to return Tuesday morning. Prosecutors and defense attorneys hashed out jury instructions Monday afternoon.

Throughout the case, prosecutors used phone calls Blankenship secretly recorded in his Massey office to let the former coal baron make their case in his own voice.

In key calls, Blankenship said that a scathing internal safety memo should be kept highly confidential, and that it would be a terrible document to show up in legal discovery if there was a mine fatality.

Former Massey subsidiary president Christopher Blanchard testified under an immunity agreement with the government, but helped the defense during almost five days of cross-examination.

He told Blankenship's attorneys that he himself did not break any laws and denied being involved in a conspiracy with Blankenship to violate safety regulations. The defense showed Blanchard more than 180 documents to get him to agree that Blankenship and Massey pushed for safety.

Testifying to prosecutors, Blanchard said he believed Blankenship thought it was less expensive to pay fines than pay for measures to prevent safety violations. He also said most Upper Big Branch violations could have been prevented by hiring more miners or spending more time on safety tasks.

And former Massey safety expert William Ross, who gave the tough review of the company's safety shortcomings, provided a rare emotional testimony.

He wept while testifying about how thrilled he was that he thought Massey was going to change. He also became emotional while talking about a 2009 meeting with Blankenship, in which he told the executive that Massey couldn't "afford to have a disaster."