UPDATE 1-Wife of Orlando shooter could face charges soon -source
* Gunman's wife could be charged as soon as Wednesday
* Senator says Noor Salman is "person of interest" in probe
* Obama calls U.S.-born killer "angry, disturbed, unstable"
* Orlando mayor to open assistance center for victims (Updates with details on family center for victims; edits)
By Letitia Stein and Julia Edwards
ORLANDO, Fla./WASHINGTON, June 15 (Reuters) - The wife of the gunman who killed 49 people at an Orlando gay nightclub could face criminal charges as early as Wednesday after a federal grand jury was convened to study possible wrongdoing by her, a law enforcement source said.
Omar Mateen's wife, Noor Salman, knew of his plans for what became the deadliest mass shooting in modern U.S. history, said the law enforcement source, who has been briefed on the matter.
U.S. Senator Angus King, a member of the Senate Intelligence Committee, which received a briefing on the investigation into Sunday's massacre, told CNN it appeared Salman had "some knowledge" of what was going on.
"She definitely is, I guess you would say, a person of interest right now and appears to be cooperating and can provide us with some important information," King said. Continuación...