He has not plead guilty to the allegations in this civil suit.  If you read the Oregonian's article that Science Duck posted, it says that the shooters were totally unaware that they hit anyone.  There was a big forested area between them, about 100 yards wide.  There is no way that the shooters could have possibly seen her.

Fields was shooting handguns with his girlfriend at the time.  I would give good odds that it was probably his girlfriend, who most likely fired the errant shots, and not Fields himself.  Very few women are skilled or experienced at shooting handguns.

The handgun would have to have been very badly aimed way too high, in order for the bullets to make it over the trees, and then come down where the victim was hit.  To me, this sounds like it was a naive and new shooter struggling to control the gun, causing it to shoot over the target.

I wonder if the police did ballistic tests, to determine which handgun shot the victim?   One would think that they would have.