What is your normal policy for when you suspect theft? What is your policy for unexcused absences? How would you have dealt with an employee who was a no show for this type of meeting had you not known he had HIV? I would follow those policies.
ADA doesn't protect him from having to follow laws/employer policies. It does require reasonable accommodation. But long absences from work are not always viewed as reasonable....the main point of ADA is to accommodate SO THE EMPLOYEE CAN WORK.
And with ADA, the employee has to interact with the employer not only to come up with reasonable accommodations but to give documentation of the disability. If they do not, then they fail on their side of the burden.
You do need to make sure theft charge is not pre-textual....what documentation do you have?

