As the staff member is new I would get them on TS3. I would remind them that they should not abuse their powers that they had been trusted with. Also, I would tell them to only use their powers in a way that could benefit the server and they shouldn’t be used to gain an advantage over players. I would tell them that if it happens again that they would be brought up in the lead team meeting for an official warning or, depending on what rules had been broken, a demotion.