Al-Hallaj was arrested around 908, held for years, tried and executed in 922. The length of that process is the best evidence that his case was not simply a theological one. Baghdad in this period was a court in permanent factional crisis, and he had supporters inside the administration as well as enemies; his prosecution was pressed hardest by the vizier Hamid, and it moved when the political balance moved.
The charges were mixed. He was accused of claiming divinity, and separately of association with the Qarmatians, a revolutionary movement then attacking the pilgrimage routes, which made him a security matter rather than a doctrinal one. The point on which his opponents finally secured a legal ruling is reported to have been narrower and stranger: a passage in his writings suggesting that a person unable to make the pilgrimage might perform an equivalent rite at home. That could be construed as denying an obligation of the law, which was actionable in a way that ecstatic speech was not.
He was flogged, mutilated, hanged on a gibbet and finally beheaded, and his body was burned and the ashes thrown into the Tigris. The judgement did not hold. Within two centuries the Sufi tradition had made him its exemplary martyr, the lover executed for saying in public what everyone in the circle knew, and Attar, Rumi and the Persian poets after them fixed that image permanently. The atlas records both: a real execution on mixed charges, and a posthumous figure who has outlived every party to the trial.