A few hours after the police arrived, an officer spoke to the media waiting outside the house (in the cold/dark night). He said something to the effect "we have no signs of forced entry". Reporters got really excited.
Here is what the police chief says about that statement:
"The reason police initially said that “there was no sign of forced entry” was because the north Toronto neighbourhood where the Shermans lived had seen a spate of break-ins and the officer was trying to reassure the public. “That community was incredibly alarmed,”"
Family of Barry and Honey Sherman offers $10-million reward for information on murder of billionaire couple | The Star
The police spent six weeks on the site, and I'm sure during that time they figured out how the intruders got in.
Greenspan's criticism was that police did not immediately detect how intruders got in, and therefore were incompetent in declaring 'there were no signs of forced entry'.
I disagree: Naturally police would examine all the windows and doors for signs of break in. Evidently there were no obvious signs like broken glass or a busted door lock. Unfortunately the Shermans had no security system, no cameras and were reputedly careless about locking doors. Imagine how shocked police were to discover that. Plus, there was a realtor's lock box. Police had a lot of work yet to do to consider all those issues, in order to figure out exactly how entry was made.