This is simple. Congress should ensure that all evidence is preserved, records made of all damages. Videotaping and archival should be thorough.
The timing is just too coincidental, and Cheney's potential crimes too serious, to ignore this fire. The public understands, where there is smoke, there's fire.
Even if it's a complete accident, a non-Executive branch entity (besides Cheney) should preserve evidence and investigate.
At minimum, a Committee should ask for videotaping and records. The resistance from Cheney will be panicked and we can move on from there.