SACRAMENTO (CBS13) – Two key witnesses in the case against the man suspected of staring 2013’s Rim Fire have died, leading federal prosecutors to try and dismiss the case.

Keith Matthew Emerald was arrested and charged with starting the Rim Fire, which burned more than 250,000 acres – including parts of Yosemite National Park – of the Stanislaus National Forest and destroyed nearly a dozen homes. The fire burned from August 2013 to October 2013, costing upwards of $127 million to fight.

READ: Motion To Dismiss Case Against Rim Fire Suspect

Emerald, who was a hunter, had to be rescued from the scene of the fire.

Charges were filed against Emerald a year after the fire started. He is suspected of losing control of an illegal campfire he started.

However, since the beginning of 2015, two of the prosecution’s key witnesses have died. U.S. Attorney Benjamin Wagner’s office says one man died in a workplace accident back in February, while a second witness – the helicopter pilot who rescued Emerald from the fire – died from cardiac arrest in March.

Without the witness testimony, prosecutors say, it would have been hard to convict Emerald.

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“I understand that the government’s motion to dismiss will be frustrating to some,” Wagner said in a release. “However, when circumstances change after indictment, and our judgment is that a case is no longer likely to be proven beyond a reasonable doubt, it is our obligation to the defendant and to the Court to dismiss that case.”

Friday, Wagner’s office filed their motion to drop the charges against Emerald and dismiss the case.

Emerald had pleaded not guilty to the charges at his arraignment.