Alright, darkpaladin didn't post, so I'll go with that.
Be shy!
(1) This just makes you seem uncooperative, and therefore suspicious. They grill you until 3AM.
Tell them Smokey the Bear saved us from dying in a forest fire!
(6) They believe you, but say that means you're probably responsible for the fire.
I'm a buddy of Tim's. I knew he was hiking in the area so I was flying over around the time that wildfire was kicking off. I was forced to land because both my engines stalled somehow even though I was flying straight and level, I was nowhere near the smoke and I had plenty of fuel. Anyways, I landed soft and then managed to take off again. Didn't see a soul while all that went on, and the only thing I witnessed from the air was that there was a fire in the forest. Mostly I'm just glad my friend is alive.. If that's all, I need to go pick the branches out of the landing gear.
Buy some paint on the way back to the lodge to cover up the damage inflicted to the heli by the cougar.
(6) As you were clearly not with the group, there's not much you can do to explain the situation, so they let you go after about 20 minutes. Unfortunately, there's not much paint available nearby, especially suitable for a helicopter, so you have to call in someone to bring it.
Politely explain that I was too busy running in panic most of the time and can't be considered a valuable vitness.
(4) They believe you, and you sit outside while they question the others.
Say that Ivan tried to kill me as well as started the fire. He is obviously a murderous psychopath!
Back up Vic with more explanation of Ivan's nuttery
(6+4) The sheriff agrees it's pretty obvious that there was some foul play here, but also that it wasn't one-sided. You're kept there till 3AM, answering more questions.
I am Starn, a old half nuts trapper following the group for setting fire to my secret beer stash.
(3) You are Starn, an old half-nuts vagrant who lives illegally in the wilderness and sustains himself by trapping. You soon learn that those responsible for burning down your home stretch have been taken in for questioning, at the Sheriff's station several miles down the road.