I am going to be running a campaign for three (possibly more) players over the summer and through the next semester (if it lasts that long).
The thrust of the campaign will focus on the acolyte's actions during a major conflict between two inquisitor's (Their master, and Lady Amaros).

So far the first session is most developed. It starts with the players meeting at a safe house on hive Sibilus on Scintilla, their orders are to find a thief who has somehow been getting into fortified and well secured spire manses and stealing select items. Normally this would be below an Inquisitor's attentions, however what caught his interest was the fact that every item stolen was of Xeno's origin (ranging from benign statuary to more dubious but not outright illegal devices and artwork), thus it falls to the acolytes to determine whether this thief is a lone xenophile or if he is working towards darker ends.
After receiving their mission the acolytes are able to pursue their leads as they see fit. Going to the noble’s estates will elicit cold and guarded cooperation if the players can prove their credentials. Of course some witnesses who wish ill of the affected families may provide more useful information (such as what the man looked like, peculiar equipment he was using, how he got into the manse ect ect)
Combing the middle-hive gets them a tip that some hotshot cat burglar went into hiding in the underhive, something about being double crossed by someone in high places. This may be given by the guy’s old fence or even a rival of his as well. If the Acolytes know of any unusual equipment the man was using they may also find the supplier and possibly get a name out of him.
If word gets around that someone other than the greencoats is coming after him, the thief will send some assassins after them, if the players search the bodies of the would be assassins they will find tattooing that marks them as members of a specific gang which only has holdings down in the underhive.
When the players feel that they have enough clues and decide to go down into the underhive to find this guy, it will turn out that he (and the gang ) have built a shanty fortress inside the ruins of an ancient Cathedral, with running water, power and some heavy machine guns. How the players get in is up to them, assaulting it would be practical suicide without allies to soak up some fire (such as a rival gang or even a roaming band of redemptionists… if the players can convince them). They could try to sneak in, or they could attempt entry under false pretenses.
Regardless of what they do in the underhive, they will be making secret(very very difficult) awareness tests to notice a man in a chameoline cloak seemingly following them through the underhive, always to far away to speak too and when they attempt to get closer he disappears before they can get to him.
If the characters kill the thief he offers in his dying words a warning to the PC’s roughly summed up as “Never work for an inquisitor… they screw you over in the end…”
If the characters succeed in capturing the thief he will cooperative but distraught and will spend his time begging for his life/leniency (His life if it is revealed that the players are agents of an inquisitor, leniency if all he know’s is that one of the characters is an arbitrator). On their way out the cloaked man will fire a sniper rifle shot at the head of the thief(firing from one of the other holes in the ceiling). This will most likely instantly kill him, however if the acolytes can stabilize him quickly enough they may be able to bring him back alive (albeit badly brain damaged)
If the characters don’t kill the thief and fail to capture him , he will attempt to escape by using a grapnel to ascend into a hole in the ceiling. He will be promptly shot by the assassin. Again if the characters are able to stabilize him they will be able to bring him back to their master (though this time on a stretcher san’s lung and with many broken bones)

If the players manage to wound the assassin, by the time they are able to reach where he was and follow the blood trail, he will be long gone and the trail will only lead them to where he allowed himself to stop long enough to patch up.
If they manage to outright kill the assassin, they will only get his gear and a small paper with the theif’s picture and personal information, with the words “Liquidation Order” and a black Inquisitorial =][= stamped on the bottom.

After all is done and the players send a report back to the inquisitor, He will be exceptionally pleased if they managed to bring the man in alive, and will be extremely disturbed by the assassination attempt. In any case he gives them a small stipend as a reward for their service (between 10-50 thrones depending on how well the mission went) and a paid ticket for each acolyte offworld and on to their next assignment.

Before i flesh out what is actually going on beyond that first mission, i would like to know if the Hayde Locks (and by connection, the Tyrant Star) and/or Lady Amaros are detailed anywhere outside of the radical's handbook and Disciples of the Dark Gods?
Also thank’s in advance for any suggestions/criticism.

Don't leave an execution order on the assassin's body for the pcs to find. That's blatantly obvious and the Inquisition would work far more subtle and with less evidence.

@Combing the Middle-Hive
I can´t imagine that one will find out that "a thief went into hiding" simply by "combing the middle hive". If a lot of people would be in the know, some of them would have either announced this to the magsitrate...either because middle hivers simply aren´t criminals and/or to cash in price money the noble houses surly will have put up for tips about the thief.

My advise : work with the "gear link" you mentioned. Have other hints the point to a person and if they try to put him down, make it known that this person "disappeared" and that he was seen talking to some scum with this-and-that colours. Which in turn lead to the gang and the underhive.

@The stealth cloak guy
Make sure you know where the =I= assasine starts following the pc. Was he expecting them? If so, where did he took up the trail? If not, how did the pc caught his attention? Perhaps he was not following them at all but was in hiding around the "shanty fortress" (?) for days (like a military sniper would), just waiting for the moment where his target would show his head so he could pull the trigger and end the assignement. The fact that the pc drove his target out of the fortress would have been a luck on his behalf, then.

@The final words
Sorry, but this is a little obivous of a spoon feeding. Especially since the soon-to-be-dead thief has no reason to believe that the pc aren´t hitman send by the =I= who is after him. It is not like he would know much of the =I=, nor does he?
Problem: I do not know how to do it better then this

@efidm

Very good point, Perhaps only finding the man's picture would get across the message that someone wanted him dead and there is a connection without spoonfeeding that it is an Inquisitor's doing.

@Gregorius21778

By "Combing The middle hive" i mean't that they would eventually find his old fence or someone who helped him disappear. Perhaps if they manage to get a photo of the guy(doing that would require a bit of mucking about the noble's security systems but they would get something) then go searching the middle hive would turn it from "near impossible" to "Difficult but doable". Finding old aquantences dead during the investigation sounds like a good way to point towards the gang, thank's.

Good advice on the whole. I intended the assassin to be already looking for the guy and was trying to get the thief out of the hideout when the PC's arrive at the scene, it was just a stroke of luck on his part yes.

I am thinking i should scrap the final speech and just have him curse out the acolytes/the dead gangers in frustration.

Hi Juggernaut,

@"The Ganger scum"
Well, my sentences where so misconstruct one had to get it wrong. My idea was that after the pc know whom they are locking for (the security system is a good point, the problem is that any and every professional is going to mask himself!) they find out form his neighbours, peers or other people that he (=the soon to be caught thief) disappeared and that he was seen talking to gangers.

Having the gangers wipping out "potential traitors" is a great idea, so. As long as the thief is a sociopath or does not have any real friends, so

So, it is "links to the identity of the thief":
a) He used special gear
(Logik; Evidence on the Scene, Security picts) which makes the pc looking for special fences
This will either lead them to a corpse and the gang link or to a fence whom they must interrogate. Perhaps this fence has "cover" of the local syndicate in the form of some muscle hanging out near his "shop"? Muscle he can call in with the push of a hidden button.. after all, he sells high gear and might have the money to pay for protection. Or it is very hard to come into contact with him. perhaps the pc can persuade him, if they make clear who they are and that they do not care about a fence, but about their target. "You decide which way we will this, gent..."

b) Inside Source.
By the way he moved through the area (security picts!) it is clear that he knew where to go and what was where. He either visited the places before or knows somebody "on the inside". If the first thing is true, it the thief might be in league with an "Adden Adale", a musician who can be hired for certain events and later sells the information of the layout to the thief. The pc will need to get the hint (Logic; brains of the players) and a little more Inquiry to ask the right questions in the right way. At the end, they need to track down the musician. Which might play out the same was as described under the gear link.
If the thief was in himself before, how about making him a secret call boy? His profession is that of a hairstylst. His secret is that he seduces the ladies o f the households. Like it would just be "for thrills". Afterwards, he plays the curious about xeno art and ask to be shown some. The ladies do so...in sectret. They are not inclined to tell this, so. Their fathers/husbands might not be please... same strategy as with the "inside man", but the Inquiry should be mixed with "Scrutiny" to determine that in each of the households their is a lady that hides something from the pc....

c) Follow the trail
In order to steal in the spires, one needs to get into the spires! In a "recent" case (perhaps the morning the theft is revealed) the pc will be able to follow a trail. Not footprints... but a "and before he was at the door, he need to get into this room... how? Through the ceiling luming panel! How did he got inbetween? He used the small service ducts from the outside!...) This can depend on the pc brains, sight based perception, security and logik. At the end, the pc end up in the middle hive at the entrance of a service duct. Screwed shut. In the backyard of the shop of the thiefs "front business" (hairstylist)? The owner is missing (see above; either the thief is the owner nd was seen with the gang since he talked to them to get some help for hire or the shop owner got money from him and he asked the gang members to get rid of him to "kill all links to him".

I hope these ideas are helpful