On 21 August 1940, Trotsky was assassinated in Coyoacán, where he had continued to live after leaving La Casa Azul. Kahlo was briefly suspected of being involved, as she knew the murderer, and was arrested and held for two days with her sister Cristina. The following month, Kahlo traveled to San Francisco for medical treatment for back pain and a fungal infection on her hand. Her continuously fragile health had increasingly declined since her divorce and was exacerbated by her heavy consumption of alcohol. Rivera was also in San Francisco after he fled Mexico City following Trotsky's murder and accepted a commission. Although Kahlo had a relationship with art dealer Heinz Berggruen during her visit to San Francisco, she and Rivera reconciled. They remarried in a simple civil ceremony on 8 December 1940.