How was Renoux discovered?

Question

In The Final Empire, after Kelsier and Vin go to meet up with Marsh for the second time since he joined the Ministry, they get to the rendezvous to find what they believe to be evidence that

Marsh has been tortured and killed by the Steel Inquisitors.

Once they find this out, they send a message to Lord Renoux to shut down their operation and hide at the safehouse.

However, on the way, Renoux, Spook and the staff

are captured and sent to be executed.

We find out at the end of the book that

Marsh has not been tortured, but has instead been turned into a Steel Inquisitor, and has remained loyal to the crew, which is shown when he kills a number of other inquisitors.

So if

Marsh never gave up the crew,

how is it that Renoux was discovered to be a spy?

Answer 1

From the Mistborn Annotations¹ on Brandon Sanderson's site:

By the way, the reason the Lord Ruler’s army attacked Renoux was not because they broke Marsh. It’s because the Inquisitors–still tracking Vin–finally managed to trail her to House Renoux, and therefore to Valette Renoux. They hit the convoy, fully expecting her to be on it. When she wasn’t, they devised their trap, knowing that Kelsier would come for his friends. They never even suspected that the team had managed to get a mole into the Ministry ranks.

So this particular bit of action seems to have occurred behind the scenes, but to answer your question: No Marsh did not give them up under torture, Vin was unknowingly tailed to the Renoux manor.