LONDON (AP) — A British judge says a wealthy Russian businessman who collapsed near his home outside London died from a heart attack.

Alexander Perepilichnyy collapsed while jogging in November 2012. Police initially said the 44-year-old died of natural causes, but foul play concerns increased after ex-Russian spy Sergei Skripal was poisoned with a nerve agent in the English city of Salisbury earlier this year.

Perepilichnyy had been helping Kremlin critic Bill Browder expose an alleged $230 million Russian tax fraud before he died.

Judge Nicholas Hilliard, who oversaw a long-running coroner's inquest into the death, concluded Wednesday that "it is more likely than not he had died from natural causes," namely sudden arrhythmic death syndrome.

He said the other potential cause of death, poisoning, couldn't be ruled out but was "unlikely."