Jain and the bank's other co-CEO Juergen Fitschen announced Broeksmit's death in an internal mail to Deutsche Bank employees.
When asked about the death, London's Metropolitan Police issued a statement saying a 58-year-old man had been found hanging at a house in South Kensington on Sunday afternoon and been pronounced dead at the scene. Police declared the death non-suspicious.
Broeksmit, a U.S. national, was an instrumental founder of Deutsche's investment bank and one many bankers, including Jain, who joined Germany's flagship lender from Merrill Lynch in the 1990s, when Deutsche launched plans to compete on Wall Street.
Broeksmit was also a principal actor in Deutsche's efforts to unwind its riskier positions and to reduce the size of its balance sheet in the wake of the global financial crisis.
His death comes at an uncomfortable juncture for Jain and Fitschen, whose reign has been dogged by poor results and legal troubles since they took over from Josef Ackermann in 2012.
"He was a dear friend and colleague to many of us who benefitted from his intellect and wisdom," Jain and Fitschen said in the internal email on Broeksmit, a copy of which was obtained by Reuters. A spokesman for the bank declined to comment.
The two CEOs are expected to defend their reform record at the bank's annual news conference on Wednesday. Last week, they revealed that litigation and restructuring costs had pushed Deutsche to a surprise loss in the fourth quarter of 2013.
Broeksmit, who worked as head of risk and capital optimisation, was viewed as one of Jain's closest allies and a key player in the bank's attempts to recover following the financial crisis.
Jain sought to have Broeksmit join the management board as head of risk management in 2012. But in a major setback for both men, German regulator Bafin blocked the appointment, saying Broeksmit lacked experience leading large teams.
Bafin was not immediately available for comment. The Bundesbank, which also oversees Deutsche, declined to comment.
Broeksmit worked alongside Jain at Merrill Lynch before joining Deutsche in 1996 as part of group of roughly 100 bankers who, alongside Edson Mitchell, formed the core of Deutsche's new investment banking business.
Mitchell, one the bank's most powerful executives, died in a plane crash in 2000.
Broeksmit left Deutsche in 2001 but rejoined in 2008 as Deutsche and other investment banks struggled during the financial crisis. He filled senior roles and reported to Colin Fan, head of markets and co-head of corporate banking and securities. Broeksmit retired from Deutsche in February 2013.
"He was considered by many of his peers to be among the finest minds in the fields of risk and capital management," the internal email said.
After handing over the reins to Jain and Fitschen in 2012, Ackermann became chairman of Zurich Insurance. But he resigned last year when the Swiss insurer's finance chief Pierre Wauthier killed himself and blamed Ackermann in a suicide note.