A British man who was poisoned by a military-grade nerve agent in an episode that killed his partner and substantially worsened relations between Britain and Russia was released from a hospital in Salisbury, England, on Friday.

The man, Charlie Rowley, 45, and his partner, Dawn Sturgess, 44, were poisoned by the chemical on July 1 in Amesbury, in southern England, after handling a small bottle of Novichok, a nerve agent developed by the Soviet Union.

Both Mr. Rowley and Ms. Sturgess were hospitalized after being found unresponsive, and Ms. Sturgess died on July 8.

Their case was linked to the March poisoning of a Russian double agent, Sergei V. Skripal, and his daughter, Yulia. British authorities say the Skripals were poisoned by the same nerve agent, though Russia has denied the accusations that it was to blame.