Yesterday a district criminal investigator told Meade that this damage took place on Wednesday night, and Meade got the photographs today:
And let's look at those pictures and think about the question who put handcuffs on the doorknobs that night. The doors have their own locks. Why would the police add more security to the doors than what is provided by those locks? Battering the doors causes the damage you see in those photographs.
And the police were on the scene to protect the Capitol, not abandoning the building. I think that from their perspective, they would not want more security than provided by the locks. Moreover, handcuffs on the doorknobs could be deadly in the case of a fire or some other imminent need for egress.
In addition, when Meade saw the handcuffs, the police had already retreated from the scene. There were protesters in the area. Meade and another observer thought they didn't look like police handcuffs (because they weren't sufficiently shiny and substantial). In the enlarged photograph, you can read the serial number on the handcuffs: 019989. (The second and third 9s could be 5s.)
Finally, the police have not made a statement saying that they handcuffed the doors shut. I think this is a big enough issue that the police should now say whether they did it or not.
ADDED: Meade showed the handcuffs picture to several police officers at the Capitol today (3/11). The first police officer Meade showed the picture to said the handcuffs didn't look like police handcuffs because they were "shitty." He also said that handcuffing the doors is not something the police would do. Eventually Meade made his way to the office of Wisconsin Capitol Police Chief Charles Tubbs, who said he would call him back. Meade left his name and number, and we await Tubbs's call.