I'm also of the opinion that this timeframe was chosen for a reason. So many folks accessing the home, going in and out, only muddies the waters and distances the perpetrator(s).
TPS said they do have video surveillance from the area so I'm hoping if TPS had done witness statements/interviews that somewhere in there a person IF they were involved messed up by saying they weren't in the area around the time of the murders but is seen on the surveillance videos. JMO