(( I’m assuming that before you left, the inspector gave you all the relevant information you need that he had - and items, such as the key to Diana’s house, the authority to see her body at the morgue where a post mortem was conducted etc - as things come up that you should have, you will have! ))
Kaelin, no-one is watching the house, Warran probably is very familiar with how the messangers work, they access a house via a servants entrance, their messages are usually left in one place, they memorise them, destroy them and deliver them verbally. They are almost universally ex soldiers, decorated special forces or undercover agents who have been tortured and resisted - they are used as a far more secure messaging system than the post. Messangers are as protected in law as majordomo’s and butlers hence why the police couldnt even intecept the message to Warran in a murder investigation, in theory the messanger could have insisted the room was empty of everyone except Warran and the police at least would have had to comply, had Aulexis insisted on remaining, he would not have had to deliver the message- indeed he probably shouldn’t have delivered it. With access to nobles houses at all times and access to their secrets, it’s a difficult, ardous profession that is highly paid and they often bear the brunt of noble rivalry. If any should take a bribe or are even suspected of having done so, their guild acts quickly and with renowned brutality. They pride themselves on their incorruptibiliy and honour.