German authorities are investigating a knife attack on a Dresden tram that left a 21-year-old American tourist with severe facial wounds after he intervened to stop two men from harassing a female passenger shortly after midnight on 24 August. Police say the assailants fled when the tram reached the Goldener Reiter stop, and the victim was taken to hospital in serious but non-life-threatening condition. A 21-year-old Syrian national was detained near the scene on Sunday but was released within hours for lack of evidence. Prosecutors announced on Tuesday that the same man had been rearrested after new information linked him to the assault. Investigators are still searching for a second suspect and the weapon used in the stabbing, and have appealed for witnesses and video footage. The U.S. Embassy in Berlin condemned the "brutal attack" and urged German authorities to "swiftly bring the perpetrators to justice." The case has revived discussion in Germany about migrant crime and policing policy, coming amid other high-profile acts of violence linked to recent arrivals. Police said the victim, a part-time model and newly qualified paramedic from New York state, is expected to recover.