Suspension of Employees from Work During Investigations

"I have an employee, who has become increasingly uncooperative and difficult to deal with, has been extremely rude and aggressive towards fellow employees and management and has been acting inappropriately causing some employees to describe his behaviour as bullying. I am worried about having this employee on site while we investigate these allegations. How do I handle it?"

The employer in the above scenario will need to make a decision, as to whether it will suspend the employee (with pay) pending investigation, or whether he will remain on site working whilst an investigation is carried out. 

Suspension of an employee pending investigation (even with pay) is not always necessary or