Devinderjit Sivia, 49, was arrested in January on suspicion of murder after police discovered the body of 50-year-old Professor Steven Rawlings at Sivia’s home. The pair had been friends for 30 years and even wrote a book together.
Chief crown prosecutor for the Thames and Chiltern Crown Prosecution Service (CPS) Baljit Ubhey said: “Following inquiries by Thames Valley Police, I have concluded, in accordance with the Code for Crown Prosecutors, that there is insufficient evidence to put before a court.
“Professor Steven Rawlings died at the Oxfordshire home of a friend on Wednesday January 11 2012.”
Ubhey added: “A post-mortem examination was conducted, but was inconclusive and further tests were required.”
Rawlings’ widow, Linda, showed support for Sivia following her husband’s death.
In a statement released through police, she said: “I do not believe that Steve’s death is murder and I do not believe Devinder should be tarnished in this way.
“Steve and Devinder were best friends since college and I believe this is a tragic accident.”
It remains unclear how Rawlings died. The CPS said that an inquest would take place in due course.