Those calling for a speedy conclusion to the congressional investigations into Russian election meddling are either doing so for strictly political reasons, or they have no idea how long investigations take and what is required to do them well.

Recent indictments filed by Special Counsel Robert Mueller in the Russia probe (and the prospect of others) should have already demonstrated to congressional investigators pursuing similar lines of inquiry that there were crimes committed, that there was a cover up and that much likely remains to be done to reveal the full extent of wrongdoing.

And yet, there are concerning reports that some congressional investigators are aiming to conclude their work as early as this month.

As a corporate investigator who was a part of multi-year probes into matters of far smaller magnitude, I know that investigations of the scope and complexity of those currently being undertaken by the congressional committees must be done diligently and conclusively, leaving no question unanswered. Financial crimes, which have already played a significant role in the Russia meddling investigations, are notoriously difficult to uncover. For instance, in 2014, the Organization for Economic Co-operation and Development found that the average resolution of foreign bribery cases has peaked at 7 years.

It is therefore imperative that the House and the Senate intelligence committees resist the mounting pressure to wrap up their investigations. What’s more, the committees must be sufficiently staffed and equipped to continue their inquiries effectively, otherwise the entire enterprise may be viewed as theater and not actual investigations. I see a clear parallel to an internal investigation a multinational corporation may undertake following allegations of grave misconduct such as corruption or conflicts of interest.

In a typical internal investigation, a whistleblower alerts either the authorities — usually the Department of Justice, the Securities and Exchange Commission, or the Department of Treasury — or the leadership of the corporation to alleged misconduct by certain employees or management. That then sets into motion a multi-year, multi-pronged internal investigation, often conducted concurrently with the regulators.

Most corporations, in cases like these, will retain outside counsel and contract with other professional services firms to help both with audits, record retention and forensics and then carefully determine the scope and the methodology of the investigation. Asking questions about the initial allegation, whether other branches, third-parties or employees were connected and whether the incident was clearly isolated or could be part of a pattern can take a not-insignificant amount of time but are necessary to inform the investigative methodology.

If such an investigation centered on alleged violations of the Foreign Corrupt Practices Act, multiple teams of professionals would be deployed to international branches of the corporation to understand what transpired in these unique jurisdictions. Hard drives would be stripped, and books and records as well as invoices would be collected for purposes of forensic audit. Public records and local-language media would be thoroughly mined. Investigators would be trying to determine whether the alleged perpetrator has been in trouble with the law before, or if, say, the company’s vendor is owned by a family member of a local government official, or whether there were irregularities in how the invoices were processed and contracts signed, among other potential lines of inquiry.

On a sprawling corporate investigation, sophisticated software programs might well be used to digitize, sort, categorize and make hundreds of thousands of documents keyword-searchable. (We used one called Relativity). Each invoice, each contract and each email would be translated, analyzed and meticulously annotated by varying levels of attorneys and analysts, depending on the inherent importance of that document.

A tiered approach to any such investigation is critical: The general consensus is that, to ask the most effective and probing questions, the interviewer ought to be armed with details and facts, though they may occasionally choose to conduct interviews prior to concluding the document reviews and other initial phases of the investigation — each of which typically takes months.

And though much of the internal workings of the congressional investigations is still unknown, it is hard for me, given my experaience with similarly complex investigations, to understand why, for instance, with the thousands of documents made available to the congressional investigators, senators asked Trump’s son-in-law and senior adviser Jared Kushner about his meeting with the head of Vnesheconombank Sergey Gorkov back in July.

Corporate investigations of financial crimes, even those involving significantly more resources and manpower than the Congressional committees, usually take years to complete. The Russia probes present a virtually unprecedented challenge for our democracy and our systems of accountability. It is unreasonable and inappropriate to rush the Senate and the House investigations — especially when the integrity of our democracy is stake.

Diana Pilipenko is the principal investigator for the Moscow Project at the Center for American Progress Action Fund. Previously she managed corporate investigations at Deloitte, a financial services firm.