A body was found in a suitcase in the bay.
"It is a homicide, but we're not releasing the cause," San Francisco police spokeswoman Lt. Lyn Tomioka said.
She said investigators have determined how Louis died but do not want the information released to the public yet, citing an open investigation.
Louis was reported missing at about 3 p.m. Monday, Tomioka said. The suitcase was found floating in the water near the Embarcadero and Folsom Street shortly before 9 a.m. Tuesday. No identifying information was found on the suitcase.
Tomioka said police have no suspect information at this time.
"We are appealing for the person or persons responsible for this, please come forward," Tomioka said.