FOR 17 MONTHS, Russian authorities have resisted taking action in the case of Sergei Magnitsky, a 37-year-old lawyer who died from mistreatment in prison after exposing a massive swindle involving senior police and tax officials. While conceding that Mr. Magnitsky had been abused and that embezzlement had taken place, officials have variously claimed that evidence necessary to pursue the case was destroyed in a mysterious vehicle explosion or that Mr. Magnitsky himself was guilty of the crime he uncovered.

Now, thanks to the efforts of lawyer Jamison Firestone, who was Mr. Magnitsky’s employer, and investor William Browder, who hired his firm, powerful new evidence has appeared. The two men have compiled documents and produced YouTube videos demonstrating the enrichment of five police and tax officials linked to the embezzlement and the subsequent persecution of Mr. Magnitsky.

The latest video, released last weekend, relies on property and bank records to show how the head of a Moscow tax office, Olga Stepanova, and two deputies poured more than $40 million into Swiss bank accounts and luxury properties in Moscow, Dubai and Montenegro soon after signing off on a bogus $230 million tax refund. The refund was processed in one day — Dec. 24, 2007 — and given to companies that were illegally seized from Mr. Browder, an American-born investor in Russia who was expelled from the country in 2005.

Two other videos show how two police officials involved in seizing the companies and then in imprisoning Mr. Magnitsky, Lt. Col. Artom Kuznetsov and Col. Pavel Karpov, have also spent millions on real estate, luxury cars and foreign travel since the swindle. Like other police officials involved in the case, they have been promoted and given awards since Mr. Magnitsky’s death, even while living like moguls.

Though it involves hundreds of millions of dollars and a wrongful death, the Magnitsky case is an example of mid-level Russian corruption. The most senior official involved is a deputy interior minister, and Prime Minister Vladimir Putin and his circle are untouched. Despite that, and the overwhelming evidence posted on the Internet by Mr. Browder and Mr. Firestone, the officials involved continue to enjoy impunity. That they do so is an extraordinary testament to the lawlessness and the disregard for basic human rights that prevail in Russia — and that the Obama administration, in its zeal for a “reset” of relations, has largely ignored.

While outside powers cannot change this culture, legislation before Congress could provide some leverage. Bills drawn up by Rep. Jim McGovern (D-Mass.) and Sen. Benjamin L. Cardin (D-Md.) would oblige the State Department to deny visas and freeze the assets of all Russian officials involved in the Magnitsky case. Mr. Cardin has identified more than 60.

The Obama administration, of course, already has the authority to impose these sanctions and has been studying the Magnitsky case. It should act against those persons it finds culpable. Meanwhile, the administration can take a positive step by seeking funding for the support of Russian democrats and civil society organizations that are fighting for the rule of law.