The jury in the federal trial of former Massey chief executive officer Don Blankenship told the judge in the case that it was deadlocked on charges Blankenship faces for his role in the mine blast at Massey’s Upper Big Branch Mine that killed 29 miners in 2010.

U.S. Disrict Judge Irene Berger told jurors to keep trying to reach a conclusion, Reuters reported.

The jury sent Judge Berger a note saying it was still deadlocked and asked for instructions. Berger then issued an Allen charge, or an order to keep deliberating, which can be used to dislodge jurors from entrenched positions.

Defense lawyers had objected before Berger issued the charge, and the judge turned down their motion for a mistrial. Berger also agreed to prosecutors' request that the jury be instructed that it can return a partial verdict on the charges.

Blankenship faces three felony counts over allegations that he ignored hundreds of safety breaches at the mine. The jury told Berger in its second day of deliberations that it could not reach a verdict, but the judge told it to keep working.

If convicted on all charges, Blankenship faces up to three decades in prison. Massey Energy was bought in 2011 by Alpha Natural Resources Inc for about $7 billion.