For the heretical crime of xenophilia, he was removed from office but secretly spirited away by the Ordo Xenos -- instead of being executed -- to serve the Deathwatch in their hunt for the "The Guiding Hand" conspiracy of pro-T'au sympathisers in the Reach.
Governor DeLacre was originally spirited out from the quarantined worlds on the orders of Inquisitor Vils Andarion. The formerly-prosperous Frontier World of Kaggeran was sliding into xenos heresy long before the Achilus Crusade arrived, and it seems the bloody war in the Canis Salient proved too great a temptation for DeLacre.
Under his corrupt regime, weapons and supplies were funneled to both sides of the conflict, DeLacre pocketing profits from stalwart crusaders and secessionist revolutionaries alike.
Such crimes would be worthy of a public and grisly death as a lesson to others, and Inquisitor Andarion had gathered evidence to make it so. However, as events transpired, Lord Commander Sebiascor Ebongrave's blockade came into place and prevented Inquisitor Andarion moving in time to stop the whole Kaggeran System slipping into anarchy.
The Inquisitor decided DeLacre could now serve a more useful purpose alive, revealing the extent of his contacts on Kaggeran, than dead at the hands of Ebongrave's Astra Militarum purity platoons. More importantly, Arman had come to believe that the web of intrigue stretched further, with the nearby systems of Argoth and Rheelas also implicated.
To forestall any argument, Andarion staged a fake execution for the benefit of Lord Commander Ebongrave before transporting the distressed but very much alive DeLacre to the Deathwatch's Watch Fortress Erioch.
A prisoner like DeLacre would normally be kept in the watch fortress' Inquisitorial Tower of Brass, but Inquisitor Andarion petitioned for the xenophile governor to be imprisoned with the other alien scum in the Xenos Bestiarium so that he could ponder his choices in allegiance.
The corrupt governor of Kaggeran is still alive because he represents the only solid link the Ordo Xenos has found to "The Guiding Hand," a wide-ranging conspiracy of secret T'au supporters among the Imperium's elite in the Jericho Reach.
DeLacre is being slowly and carefully wrung dry for every scrap of information he can give. Some of the names emerging are highly disturbing to see and the Officio Assassinorum has already been alerted.
Inquisitor Andarion's decision to keep DeLacre locked up in the Xenos Bestiarium may in fact be motivated by a lack of trust in his Inquisitorial colleagues and their retinues.
- Deathwatch: Rites of Battle (RPG), pg. 242