Four U.S. senators who met Friday with the families of 12 coal miners killed at the Sago Mine vowed to find answers about what caused the Jan. 2 explosion, what went wrong afterward and how mine safety can be improved nationwide as a legacy to the lost men, the Charleston (W.Va.) Gazette reports.

Sen. Edward Kennedy, D-Mass., said he was troubled to hear that the families have not yet been involved in the accident investigation. He urged state and federal investigators to take time to talk to the relatives, who he said are extremely knowledgeable about the industry.

Investigators have yet to determine the cause of the explosion that resulted in the deaths of 12 members of a 13-man crew at International Coal Group’s Sago Mine in Tallmansville, Upshur County. Survivor Randal McCloy Jr., 26, continues to improve and remains in a “light coma” at a West Virginia hospital.

Kennedy accompanied Sen. Jay Rockefeller, D-W.Va., to the meeting at West Virginia Wesleyan College with Senate Health, Education, Labor and Pensions Committee Chairman Mike Enzi, R-Wyo., whose committee oversees mine safety, and Sen. Johnny Isakson, R-Ga., chairman of the subcommittee on employment and workplace safety.

Sen. Robert C. Byrd, D-W.Va., stayed in Washington to prepare for Monday’s hearing, the first congressional oversight review of federal mine safety programs since 2002.

Also Friday, a spokesman for the United Mine Workers said the union has not yet agreed to be excluded from interviews that state and federal authorities are conducting as part of the investigation of the Sago explosion.

UMW spokesman Phil Smith said the union stayed out of Thursday’s interviews so they would not be delayed, but that UMW officials have not agreed to be blocked from future meetings.

Earlier this week, controversy erupted over the investigation interviews when ICG officials objected to the UMW taking part. The Sago Mine is a non-union operation, but several Sago miners took advantage of their legal right to designate the UMW as their “miners’ representative” in the investigation.

At Friday’s meeting with the senators, relatives of the Sago miners came armed with a long list of recommendations to make mines safer. Kennedy said their suggestions included better surface-to-mine communication systems, better escape-and-rescue communications and pre-positioning lifesaving materials in the mines.