In the wake of revelations about the infamous Steele “dossier,” the chair of the Senate Judiciary Committee has decided to use a famous Watergate axiom — follow the money. Chuck Grassley has sent a letter to the Treasury Department seeking any records of suspicious financial transactions involving prominent figures in the Russian collusion probe. As Buzzfeed’s Jason Leopold reports, the specific people and entities Grassley cites in his demand all have some connection, direct or indirect, to the dossier and Fusion GPS:

Senator Chuck Grassley, the chairman of the Senate Judiciary Committee, sent a letter to the Treasury Department’s Financial Crimes Enforcement Network — FinCEN for short — on September 29, seeking information about any suspicious financial transactions banks may have flagged on the individuals and businesses since Jan 2015. Banks are required by law to flag such transactions for FinCEN. …

“The Senate Judiciary Committee is conducting an investigation into Russian interference in the 2016 presidential election, as well as the Department of Justice’s enforcement of the Foreign Agents Registration Act,” Grassley’s letter says. “I am requesting a copy of any and all documents relating to Suspicious Activity Reports (SARs) that have been filed regarding the following individuals or entities.”

The most direct figures on Grassley’s list are Fusion GPS execs Glenn Simpson, Thomas Catan, and Peter Fritsch, as well as dossier author Christopher Steele himself. The Fusion GPS execs took the Fifth Amendment rather than answer questions about the funding of the dossier, later revealed to have originated with the Hillary Clinton campaign and the DNC. Also in the mix is the law firm Perkins Coie, the direct link to the Hillary Clinton campaign and the dossier.

It also includes others with interesting indirect (so far) connections to the dossier. Natalia Veselnitskaya and Rinat Akhmetshin first came to prominence as the pair that met with Donald Trump Jr, Jared Kushner, and Paul Manafort for the Trump campaign’s amateurish attempt at oppo research on Hillary. However, Veselnitskaya and Akhmetshin have ties with Fusion GPS that go back even further to an alleged smear campaign aimed at ending the Magnitsky Act and its sanctions on Russia. That raises questions about Fusion GPS’ potential connection to that meeting, and whether it was an attempted dirty trick quarterbacked by the Hillary Clinton campaign. (If so, it would be just one more reason among many why it was a brain-dead move to accept the meeting in the first place.)

Buzzfeed notes this development as an indication that the Judiciary Committee’s probe into collusion has “stepped up,” but the target list for these potential financial transactions suggest more that it’s turning toward Hillary Clinton and her campaign. Leopold also notes that Dianne Feinstein didn’t sign the letter, which signals some nervousness about the potential for Democrats to get caught up in collusion. Politico had reported late yesterday that Feinstein and Grassley had stopped working with each other:

Tensions between Grassley and Feinstein appeared to rise after the Republican sent a passel of letters to central figures in the James Comey firing and the Trump-Russia nexus without the Democrat’s signature. The duo had previously collaborated on high-profile requests in their Russia investigation, including a bid for the CIA to grant their members access to classified material already viewed by the Senate Intelligence Committee.

Among the figures Grassley asked for information and interviews were Trump adviser and son-in-law Jared Kushner and Russian lawyer Natalia Veselnitskaya. Both Kushner and Veselnitskaya attended the June 2016 Trump Tower meeting, initially advertised as a conduit for opposition research that could hurt Clinton’s campaign.

Asked why Grassley would press ahead without securing her signature, Feinstein was curt. “It’s his right to send letters — you ask him,” she said Tuesday.

Fusion GPS’ link to Veselnitskaya, Akhmetshin, and Team Hillary suggests a whole new level of collusion. Feinstein’s disinterest in probing it is veeeerrrrrry interesting indeed.