Well..think of the LT as a witness to this crime who is speaking to us after the fact. What has he told us? What has his body told us?
He tells us that he saw 3 men, 2 white 1 black. Just because we can't find the 3 men, does that disprove his statement? Could there be a logical explanation why we haven't found the 3? Answer: They got away somehow.
He tells they went into the swamp. Just because there are no footprints, doesn't mean they weren't there. Answer: it's a marshy area and footprints disappear.
His body tells us it was shot twice. Logic would dictate that suicide would include only one shot. Answer: The first shot would have put him off balance and thus make the 2nd shot easier to accomplish by a killer.
The scene tells us there is unknown DNA. So their could have been several people there. Answer: possible unknown persons at scene of the crime.
This all goes along with Filenko's PC, in case I didn't make it obvious enough. But Filenko is trying to tell us the LT's story.
So in other words, given none of this other evidence, suicide theory would be a simple conclusion. No call, no DNA, no evidence of a struggle, only one shot, etc...but since we have all of those things lined up telling one story, in my opinion, it needs to be disproven that these things are as they would seem.
Now let's think about what all of that evidence may have meant if the LT was still alive when they reached him. Would you be inclined to believe what he is telling you? He is a 30 year veteran, a family man, a good cop, a US veteran, a pillar of the community, etc...would you even doubt his story for an instant, at first blush? Probably not. So it stands to reason that they are investigating this as a homicide based on the story that was presented to them by their trusted officer. The evidence will either match up to his story or not. So far, many of the things we know actually do match up to his story. Unknown DNA. Evidence of a struggle. 2 shots. The radio call. Etc... So in order to change the investigation to a suicide investigation, in my opinion, there needs to be specific evidence pointing back in that direction. At this time, there appears to be no direct evidence pointing back that way that isn't speculation. To me, the lack of evidence is not evidence. The lack of 3 suspects is not evidence.
So what is known at this time all points to homicide. So I ask, what evidence do we have at this time, that points directly to suicide?