Nikolai Gorokhov, a lawyer representing the family of a Russian whistleblower, was reportedly thrown out of the fourth floor of his Moscow apartment building on Tuesday — a day before the 53-year-old was due to appear in court regarding a contentious corruption case.

According to a news release from a website linked to the lawyer's spokesman, Bill Browder, Gorokhov had severe head injuries and was hospitalized in the intensive care unit of Botkin hospital. The release indicated he was in critical condition.

Some reports indicated that Russian media outlets had claimed Gorokhov's fall was an accident related to moving a Jacuzzi, but CNBC could not immediately confirm.

Gorokhov was working to launch a probe into the death of Sergei Magnitsky, a lawyer who died in prison in 2009 after claiming that organized criminals colluded with Russian government officials to claim a fraudulent $230 million tax rebate.

At the time of his findings, Magnitsky was working for Hermitage Capital Management under Browder, an American-born hedge fund boss and human rights activist who was an alleged victim in the scheme. He launched an international justice campaign following Magnitsky's death, which many activists believe was a result of abuse under police custody.