"We haven’t received assurance that the agency has taken the necessary steps to prevent future, intentional misconduct or that any employees were truly held accountable for these indefensible actions,” Rep. Louis Gohmert told The Daily Caller News Foundation’s Investigative Group.

The Texas Republican is chairman of the House Natural Resources Subcommittee on Oversight and Investigations, which is investigating the data manipulation.

Two USGS scientists manipulated data at a Lakewood, Colo., lab for nearly its entire existence from 1996 to 2014. Managers willfully neglected the falsification, and the agency learned how to prevent future manipulation as early as 2008, but the issue still isn’t fixed, TheDCNF previously reported.

The USGS has repeatedly refused to say if any person has been punished or fired for the manipulation.

Gohmert’s panel has investigated the issue since June 2016, but hasn’t uncovered many answers. The USGS gave the subcommittee a batch of documents, but many were completely redacted, making them useless.

“The more we dig in, the more questions arise,” Gohmert told TheDCNF. “We’re not talking about just a few fudged numbers, we’re talking nearly two decades of continuous data manipulation. We are still trying to understand the entire scope of the problem. Is this isolated to just one lab? Is similar misconduct happening elsewhere?”

The manipulated data regarded a variety of energy-related topics, including the quality of coal reserves and uranium deposits.

The motives of the scientists who manipulated the data are unknown. The effects are also unclear, though a June 2016 Department of the Interior Inspector General report said “they will be serious and far ranging” and that $108 million worth of projects were affected.

“For the so-called gold standard of scientific integrity and reliability, the systemic issue of data manipulation is unfathomable and entirely unacceptable,” Gohmert said. “We need to restore accountability and integrity to our federal science institutions for the sake of our hardworking taxpayers.”