Dr. Mainak Sarkar was a 38 year-old former mechanical engineering Ph.D. student of William Klug.  Sarkar immigrated to the United States of America in 2001 on a foreign student visa from India. He was granted lawful permanent resident status in May 2014.
Sarkar was confirmed by law enforcement on June 2nd, 2016 to be the killer of William Klug during the UCLA Shooting. Sarkar used a 9-millimeter pistol to shoot the professor in his office in Boelter Hall. Sarkar then immediately killed himself in Klug's 4th floor office.  UCLA professor Chris Lynch is credited for locking the door to Klug's office immediately after hearing two gunshots so that Sarkar could not engage other potential victims.
Sarkar wrote a blog article describing his hatred of Klug   The blog article was deleted but Google cached it and it was thus retrievable.   On March 10, in the blog post, Sarkar called the professor “a sick person” who stole his work. “I was this guy’s Ph.D. student,” he wrote. “We had personal differences. He cleverly stole all my code and gave it [to] another student. He made me really sick.” 
Sarkar also killed his estranged wife Ashley Hasti in Minnesota leading up to the UCLA Shooting. They had broken up and had stopped being friends on Facebook. Ashley's family members said Sarkar was absent from family gatherings, and that Hasti had kicked Sarkar out of the house, and they had been living separately.
Sarkar had a kill list with three people on it William Klug, Ashley Hasti, and an unknown UCLA professor who was not killed. After the killings, Sarkar had left a note stating his address in Minnesota and to look after his cat. 
Police found his car on June 3rd, 2016, described as a 2003 gray Nissan Sentra with Minnesota license plate 720KTW. The car was found in the Century City area of Los Angeles, California at 11300 block of Washington Place, west of Sawtelle Boulevard.  
Sarkar worked as an engineering analyst at Endurica LLC until August 2014. From 2005-2007 he worked as a software developer at Lucid Technologies. From 2002-2003 he worked as a research assistant a the University of Texas at Arlington. From 2000-2001 He worked for Infosys Ltd. in Bangalore, India.  
Dr. Mainak Sarkar graduated from UCLA with a PhD in mechanical engineering in 2013. For his PhD Dr. Sarkar took courses in Fracture Mechanics, Computational, Solid Mechanics, Finite element Analysis, Theory of Shells and Plates. While at UCLA he worked as a teaching assistant for undergraduate courses (Finite Element Analysis, Statics and Dynamics, Applied Mathematics) in Mechanical Engineering. 
In 2005, he graduated from Stanford University with a Master of Science in Aeronautics and Astronautics. In 2000 he graduated from the Indian Institute of Technology, Kharagpur with a degree in Aerospace Engineering. 
"Department of Homeland Security databases indicate that Mr. Sarkar was in the United States lawfully at the time of his death, having been granted lawful permanent residence in May 2014. According to DHS databases, Mr. Sarkar originally came to the U.S. in 2001 on a foreign student visa to pursue graduate studies. DHS’ electronic records show he obtained three student visas between 2001 and 2008 to engage in masters and doctoral programs in the U.S."