Yes, we called it "the floating timeline".
Jeff stated that he'd seen a vehicle, resembling that of the barber (who was cleared by police) driving around the neighborhood. Assuming that the driver of that vehicle was the killer, they'd have seen that Jeff was in and out. He'd gone to CVS for paper plates, and returned. If the killer was staking out the house, wouldn't they have seen him come and go?
Jeff leaves again to go to the Home Depot. The killer chooses the most narrow window of time to strike, and is incredibly LUCKY that he/she misses the cleaning woman, and Jeff's return. (How could they know that Jeff wasn't coming right back, as he had after the CVS trip?) No one in the neighborhood is coming home for lunch, or walking their dog. It's the time period where someone may have been coming home for lunch. They are so smooth they don't leave any evidence behind. They'd have had to have worn gloves, and left no DNA behind.
Bob is skirted off by someone who has nothing to gain, and does so in the riskiest of manners, yet doesn't leave a trace? If this time period is correct, then this killer is incredibly lucky, and skilled. Or, this happened overnight, possibly early morning, and someone isn't telling the truth.