[ca] Can My Employer Discipline Me For A Dog Bite That Occurred 9 Hours After My Shift Ended?

Location: California

I work security at a large hospital in California and have been there for several years. I’m union represented.
I’m looking for outside opinions, especially from anyone familiar with HR, hospital security, service-animal policies, or union investigations.
During one of my shifts, I was assigned to the entrance of a hospital unit. A patient’s support person came through carrying a small dog in his arms.
To be completely clear, I did not stop the person from entering.
As he was walking/rushing into the unit carrying the dog, I asked if the dog was a service animal. He responded that it was and continued into the unit.
I did not further question him or physically prevent him from entering.
At the time, I wasn’t aware of any information indicating that this particular dog had previously been prohibited from the unit. Nobody from nursing, unit staff, management, or other personnel told me that the dog wasn’t allowed or asked security to remove it.
I also did not personally observe the dog behaving aggressively, and no incident involving the dog was reported to me during my shift.
This is where the timeline becomes important.
The dog bite happened approximately NINE HOURS after my shift had ended and I had already gone home.
There is surveillance footage showing the dog coming in and out of the unit multiple times. So this wasn’t a situation where I interacted with the person once, the dog remained hidden inside the unit, and then immediately bit someone.
The dog continued coming and going through the area after my interaction and after I was no longer there.
Management later questioned why I didn’t intervene or stop the support person from entering with the dog. My manager’s position was essentially that I failed to take appropriate action and that the incident had escalated to higher levels of hospital management.
I was required to provide a written statement and was later placed on administrative leave pending investigation.
I understand that my employer can investigate whether I followed its internal policy correctly. I’m also not claiming that asking “Is that a service animal?” automatically means I handled everything perfectly.
I now understand that under the ADA, when it’s not obvious what service a dog provides, staff are generally permitted to ask two limited questions: whether the dog is required because of a disability and what work or task the dog has been trained to perform.
So yes, looking back, I only asked one question.
What I’m struggling to understand is what intervention my employer reasonably expected from me at that moment, especially considering the restrictions surrounding service animals.
The person told me it was a service animal. I had not observed aggressive behavior. I wasn’t told the animal had previously caused problems or was prohibited. Nobody from the unit asked me to remove it.
And even after my interaction, surveillance shows the dog continuing to come in and out of the unit.
Then, approximately nine hours after I had already left work, the dog allegedly bit a nurse.
I understand management investigating whether I should have followed a different procedure when the dog initially entered. That’s one question.
But I feel like there are two separate issues:
1. Did I follow my employer’s service-animal/security procedure correctly when I encountered the dog?
and
2. Can the eventual dog bite nine hours after I left reasonably be attributed to my actions when the animal continued coming in and out of the unit afterward?
Those don’t seem like the same question to me.
I’m particularly interested in hearing from people who understand ADA/service-animal rules. Given what I knew at the time, what would hospital security realistically have been expected or legally permitted to do after someone said the dog was a service animal?
And from an HR/union perspective, how significant would the surveillance footage and nine hour gap be when determining individual responsibility?