I hadn't seen 9PM to 6AM anywhere, but I did read the report from the police stating:
"the suspect clearly spent a considerable amount of time out and about from late at night on Saturday, June 6, 1992 into the morning of Sunday, June 7, 1992."
That time frame is interesting. It leaves the door wide open for someone to have abducted/harmed Sherrill well before the girls allegedly got to the house at 2:30 AM.
Maybe the police are still considering the sighting of a man loitering around the neighborhood to be valid- at least within the context of Saturday evening. If the police thought the only crime that occurred happened after the girls got home- then the time frame would be smaller and say something like "early Sunday morning" rather than including Saturday night as well. I can think of a few reasons why they would include Saturday evening in the time frame:
1) They know something happened to Sherrill late Saturday evening
2) They consider the 'transient' to be the suspect and he was seen by the witness on Saturday evening
3) Both 1 & 2
4) ?
I'm taking the statement "into the morning of Sunday, June 7. 1992" to mean well into the morning. Like 11 AM or later.
I would think that an abduction of three women, driving somewhere to rape/kill/abandon them, and coming back home would take some time. It could be shorter if he left them imprisoned somewhere and returned later to do his thing, but that would be much riskier than killing them right away and being done with the whole deal. With that being said, I wonder what condition his clothes were in when he got home.