According to local newspaper the Deseret News, a decision will be made within weeks and witnesses have been interviewed by investigators as the group decides whether or not to seek a grand jury indictment for potential misrepresentations.
"Oftentimes, what gets people in trouble is lying about what they knew and when they knew it," Utah US Attorney Brett Tolman told the paper.
Tolman added the investigators are looking at dishonest statements made to federal regulators as well as a pattern of problems Crandall Canyon has suffered.
"There's a difference between bad business and criminal behavior," Tolman told the newspaper, but he did not specify who would be targeted in any criminal investigation or who has been interviewed to date.
The US Mine Safety and Health Administration referred the case to the US Attorney's Office for Utah last September.
Neither MSHA nor the mine’s owner have released public statements on the case.
Crandall Canyon is owned by UtahAmerican Energy, a subsidiary of Murray Energy.
Six workers died in the initial mine collapse, including Kerry Allred, Luis Hernandez, Carlos Payan, Brandon Phillips, Don Erickson and Manuel Sanchez.
Ten days later, Dale Black, Brandon Kimber and Gary Jensen were killed during rescue attempts when a second collapse occurred.
Two civil lawsuits filed by the families of the victims against Murray Energy are still pending in the state and federal court, according to the News.
In January, the family of one of the initial six miners killed received a favourable judgment which gave the family full benefits for the next six years.
A Utah Labor Commission administrative judge has ordered Rockwood Casualty Insurance and Murray Energy to pay out $US565 weekly for the next 312 weeks to the family of Juan Carlos Payan, with payments retroactive to the date of the incident.
MSHA said last September at the time of the referral that its decision stemmed from the same facts, events and conditions that resulted in $US1.34 million in fines against the mine owner last July.
Agapito Associates, a mining engineering consultant, was also fined $220,000 for an allegedly faulty analysis of the mine's design.
“Through its investigation of the tragic accidents last year at Crandall Canyon, MSHA determined that the operator and its engineering consultants demonstrated reckless disregard for safety," then-MSHA acting assistant secretary of labor Richard Stickler said.
“MSHA has referred this case for possible criminal charges.”
Stickler added that the requested stay was necessary to avoid potential interference with the criminal enforcement process, which could arise from a contemporaneous related civil enforcement proceeding.
