VERVIERS, Belgium — Black smudges and faded traces of gunfire on a red brick rowhouse here in eastern Belgium mark the death foretold of Abdelhamid Abaaoud. It is the spot where, 11 months before the announcement on Thursday that he had been killed outside Paris, he began plotting an elaborate campaign of terror across Europe.

Mr. Abaaoud’s inaugural terror mission here ended in disaster for his cause and cost the lives of two of his jihadist friends — both from his old Brussels neighborhood, Molenbeek — when Belgian security forces stormed their hide-out on Jan. 15.

But Mr. Abaaoud was not there. A telephone call he made shortly before the raid in Verviers to pass on instructions to those in the hide-out, a senior Belgian counterterrorism official said, was the last trace anybody had of him until the French police found on Wednesday what turned out to be his mutilated body after an early-morning shootout just north of Paris.

His whereabouts had remained a constant source of mystery and suspected misinformation from his Islamic State handlers. That was, until the bloody raid in the Paris suburb of St.-Denis revealed the gaping holes in Europe’s system of open borders that allowed him to infiltrate France under the noses of the intelligence services across the Continent.