Public ReadOnly Property WasAbandonded As Boolean

public bool WasAbandonded {get;}

using (Mutex mtx = new Mutex())
{
    Thread t = new Thread(
        delegate()
        { GC.KeepAlive(new MutexLock(1, mtx)); }
        );
    t.Start();
    t.Join();

    //So the previous thread abandoned the mutex...
    using (MutexLock lck = new MutexLock(mtx))
    {
        Assert.IsTrue(lck.WasAbandonded);
        Assert.AreEqual(mtx, lck.MutexHandle);
    }
}

Using mtx As New Mutex()
    Dim t As New Thread(Function() Do
        GC.KeepAlive(New MutexLock(1, mtx))
    End Function)
    t.Start()
    t.Join()

    'So the previous thread abandoned the mutex...
    Using lck As New MutexLock(mtx)
        Assert.IsTrue(lck.WasAbandonded)
        Assert.AreEqual(mtx, lck.MutexHandle)
    End Using
End Using