kill child C#

/// <summary>
/// Kill a process, and all of its children, grandchildren, etc.
/// </summary>
/// <param name="pid">Process ID.</param>
private static void KillProcessAndChildren(int pid)
{
    // Cannot close 'system idle process'.
    if (pid == 0)
    {
        return;
    }
    ManagementObjectSearcher searcher = new ManagementObjectSearcher
            ("Select * From Win32_Process Where ParentProcessID=" + pid);
    ManagementObjectCollection moc = searcher.Get();
    foreach (ManagementObject mo in moc)
    {
        KillProcessAndChildren(Convert.ToInt32(mo["ProcessID"]));
    }
    try
    {
        Process proc = Process.GetProcessById(pid);
        proc.Kill();
    }
    catch (ArgumentException)
    {
        // Process already exited.
    }
}