“Thomas had a long and difficult sickness,” his wife Daniela told Bild. The 44-year-old zookeeper had bladder cancer, she said.
Dörflein was away from the Berlin zoo for four weeks in April, the paper reported, implying that it was a health related accident and not vacation time.
Dörflein was found dead at a friend's Wilmersdorf home and emergency services were unable to revive him. An autopsy on Tuesday revealed he had died of a heart attack. His wife told Bild that the family plans to bury him on October 13, his 45th birthday.
The mild-mannered zookeeper shot to fame along with superstar polar bear cub Knut as he raised the bear by hand in 2007. Knut drew millions of visitors and became so popular he even appeared on the cover of glossy US magazine Vanity Fair. Now an adult, Knut is showing disturbed behaviour, animal welfare groups say.