My sister has been arrested can I visit her

If your inquiry is about the visit of a convicted person, find the following information:
It is possible for you to personally review the Public Prosecution in order to submit an application for a permit for a visit. Also, you can apply online using this link:
Dubai Police website:
Dubai Police website
Or you can use the website of the Judicial Department in Abu Dhabi via the following link:
The Judicial Department in Abu Dhabi 
Or through the Ras Al Khaimah government website through the following link:

Ras Al Khaimah government website