The incident happened at about 1:30 a.m. at an apartment complex in the 300 block of East 7th Street near Long Beach Boulevard.
Authorities said they received a 911 call reporting a disturbance at the address. Responding Long Beach police officers arrived at the scene to find a man in his 30s dead on the floor of the apartment. His name has not been released.
The two apparently were living apart, and the man may have broken into the residence, according to police. Authorities said they were married for about a year.
Police initially believed the woman had attacked him in self defense, but detectives later booked her on suspicion of murder. The district attorney's office will ultimately rule on whether or not she acted in self defense.
"We don't know what the motive was. We don't know for what reason the contact turned into an assault," said Long Beach police Sgt. Rico Fernandez, who added the couple has a history of domestic violence.
The district attorney's office was scheduled to hear the evidence surrounding the case sometime Monday.