Set Identity of Thread

Question

In C#, how do I set the Identity of a Thread?

For example, if I have Thread MyThread, which is already started, can I change MyThread\'s Identity?

Or is this

Answer 1

Update for the accepted answer [apply ONLY on .NET framework 4.5 and above]
In .NET 4.5 the property IsAuthenticated has no set accessor, so you can not set it directly as the accepted answer doing.
You can use the following code for setting that property.

GenericIdentity identity = new GenericIdentity("someuser", "Forms");
Thread.CurrentPrincipal = new GenericPrincipal(identity, new string[] { "somerole" });