The Russian state-run RIA Novosti news agency reported Erovinkin's body was "found in a black Lexus... [and] a large-scale investigation has been commenced in the area. Erovinkin's body was sent to the FSB morgue".
No cause of death has been confirmed and the FSB continues to investigate. Media reports suggested his death was a result of foul play.
It was later claimed he died of a heart attack. Christo Grozev, an expert on Russia-related security threats, believes Erovinkin is the key source to whom Mr Steele refers in his dossier.
Mr Grozev said on a blog: "Insiders have described Erovinkin to me alternately as 'Sechin's treasurer' and 'the go-between between Putin and Sechin'. One thing that everyone seems to agree - both in public and private sources - is that Erovinkin was Sechin's closest associate."
Mr Grozev, of Risk Management Lab, a think tank in Bulgaria, said: "I have no doubt that at the time Erovinkin died, Mr Putin had Mr Steele's Trump dossier on his desk. He would - arguably - have known whether the alleged... story is based on fact or fiction.
"Whichever is true, he would have had a motive to seek - and find the mole... He would have had to conclude that Erovinkin was at least a person of interest."
Experts expressed scepticism about the theory.
"As a rule, people like Gen Yerovinkin don't tend to die in airport thriller murders," said Mark Galeotti, an expert on the Russian security services.
Mr Steele, 52, a Cambridge graduate, remains in hiding following his unmasking as the author of the Trump dossier.