As a retired medic who has has to deal with my share of the mentally ill, I will try to add a little context perhaps.
What got them to enter the apartment is they probably realized they were dealing with a mentally ill person who was not properly on their meds, (we can’t say for sure at this point - but it’s as likely as not), and they then started what should have been a simple welfare check. Which can entail entry to observe the person and the general living conditions. Cops do welfare checks everyday, multiple times a day. The next step if they determine there is a problem, is to request medical assistance, an ambulance, to deal with the person. The cops are to remain in scene and assist if needed - i.e. help talk the patient into seeking medical help or sometimes stop an assault on EMS. But that’s what SHOULD have happened.