Dr. Hamid Mirshojae, 61, was fatally shot after leaving his medical practice in the 5900 block of Topanga Canyon Boulevard on Aug. 23, according to the Los Angeles Police Department.
Los Angeles police Thursday arrested his ex-wife, identified as 53-year-old Ahang Mirshojae, who was booked on suspicion of murder. She was taken into custody around 10:45 a.m., according to jail records.
Three other suspects - Evan Hardman, Sarallah Jawed, Ashley Rose Sweeting - have been formally charged in the case.
Police Thursday also arrested 46-year-old Valley Village resident Shawn Randolph on suspicion of murder.
"The investigation revealed that these five persons conspired to commit murder, culminating in the ambush and subsequent demise of Doctor Mirshojae," the LAPD said.
Hardman, 41, of Tomball, Texas, and Jawed, 26, of Canoga Park, are accused of carrying out the killing for financial gain, according to a complaint. They're also accused of assault with a deadly weapon in connection with an alleged baseball bat attack May 3 on Hamid Mirshojae.
Sweeting, 40, of Reseda, pleaded not guilty Thursday to one count of being an accessory after the fact. She is accused of driving the shooter to and from the crime scene.
Meanwhile, LAPD investigators on Thursday raided a Calabasas home linked to Mirshojae's ex-wife. AIR7 was above the scene and captured several officers going in and out of the home on Newcastle Lane.
The LAPD confirmed Thursday evening that Ahang Mirshojae had been arrested.
No details were provided on Ahang Mirshojae and Randolph's specific alleged roles in the killing. Both were being held without bail, pending word on criminal charges.
Sweeting and Hardman were both arrested Tuesday. Eyewitness News has learned they each have lengthy criminal records.
Documents requesting a restraining order show Hardman was accused of threatening a woman, allegedly telling her "You'll be dead by the end of the day." Although Hardman was most recently living in Texas, the court records indicate previous cases and arrests in the San Fernando Valley.
Jawed was taken into custody Wednesday, police said.
City News Service contributed to this report.