WASHINGTON — The Justice Department appears to be laying the groundwork for an investigation into the transfer of fetal tissue by abortion providers, including Planned Parenthood, picking up where several Republican-led inquiries in Congress had dropped off last year.

In a letter to the Senate Judiciary Committee on Thursday, Stephen E. Boyd, the assistant attorney general for legislative affairs, requested unredacted documents underlying a 2016 investigation by the committee into the exchange of human fetal tissue that had been donated for research by women who get abortions.

“At this point, the records are intended for investigative use only,” Mr. Boyd wrote, adding that it might take a vote by the Senate to allow the documents to be used in formal legal proceedings.

His letter, a copy of which was obtained by The New York Times, did not name Planned Parenthood or other groups implicated in the Judiciary Committee report. Nor did it give much indication of how expansive or developed the department’s work was. A Justice Department spokeswoman, Sarah Isgur Flores, declined to comment on Friday, citing department policy against commenting on or confirming the existence of an ongoing investigation.