[5] While the investigation never proved bribery, there is evidence of efforts by both those supporting the prosecution and the defense having made offers to senators to persuade their votes.

This includes evidence of promises of patronage jobs, cash bribes, and political dealmaking being made to solicit votes for acquittal.

Evidence also suggests that Alexander Randall and Edmund Cooper (a leader at the United States Department of the Treasury) were possibly in charge of managing an "acquittal fund" for Johnson.

[6][10] Also on May 16, 1868, the House voted 88–14 to approve a resolution introduced by impeachment manager John Bingham (R– OH) that enabled the impeachment managers to investigate alleged "improper or corrupt means used to influence the determination of the Senate" and to appoint sub-committees to take testimony, with the stipulation that expenses of the investigation would be paid for from the contingent fund of the House.

The impeachment managers, during the hiatus between votes, began searching for possible corrupt means that may have persuaded senators to acquit.

[6] The investigation took a heavy-handed prosecutorial approach, subpoenaing telegrams, and looking into the bank accounts of private citizens that just-so happened to have withdrawn large amounts.

This source reported that Ward had paid Senator Edmund G. Ross for his vote to acquit with $12,000 from Democratic congressman John Morrissey.

Wilkes speculated that the transfer of money was handled by "Charley Morgan", who was a cross-dresser who was allegedly involved in separate extramarital affairs with both Morrissey's wife and Samuel Ward.

During the middle of the investigation, a young woman going by the name "Charley Morgan" was arrested in New York, pleading guilty to a misdemeanor charge of "indecency" for crossdressing.

Wendell told the committee that he had been uninterested in being part of this plan, and pointed blame on Seward's aide Erastus Webster, who it appeared had collected a fund of $165,000 for the purposes of buying acquittal votes.

This money was said to have primarily been raised by Randall, Hugh McCulloch (United States secretary of the treasury) and Henry A. Smythe through middlemen such as Perry Fuller and James Legate (a special agent of the Kansas Post Office Department), though Fuller and Legate were said to have pocketed most of the money raised for themselves.

He also said that the raising of money for a potential Chase presidential bid was being used as a front for establishing a fund to support the acquittal of Johnson.

[15] Among the other individuals interviewed was Thomas Ewing Jr.[15] Much evidence implicated Senator Samuel C. Pomeroy, who had voted to convict, in possible corruption.

[6] The committee submitted a report on their preliminary findings on May 26, hours before the Senate met again to vote on articles of impeachment.

While some senators attempted to get the trial to adjourn until the end of June to allow the impeachment managers more time to investigate before the vote.

[19] Butler led the continuation of the investigation and conducted hearings and inquiry into widespread reports that Republican senators had been bribed to vote for Johnson's acquittal.

[6][20] Conservatives charged that Benjamin Butler was intentionally targeting Ream in his successful resolution to turn her studio into a Capitol Police guardroom.

[6] After he appeared before the investigative committee and answered their questions to an extent that they found satisfactory, the House voted to discharge Woolley from their custody on June 11, 1868.

[15] It was rumored, however, that Butler hidden thirty-six volumes of incriminating telegrams in hopes he could later use them to blackmail congressional colleagues in the future.

[15] In the post-trial hearings and investigations there was growing evidence that some acquittal votes were acquired by promises of patronage jobs and cash bribes.

James W. Grimes received assurances that acquittal would not be followed by presidential reprisals; Johnson agreed to enforce the Reconstruction Acts, and to appoint General John Schofield to succeed Stanton.

Butler, perhaps, was selective with what truths he sought to uncover in the investigation, hoping only to find those that would harm the president and the Democratic Party and help the Republicans.

Fuller admitted that, at the authority of Edmund Cooper, he had offered $40,000 to Senator Samuel C. Pomeroy's brother-in-law Willis Gaylord.

[6] Being unable to definitively prove that bribery took place, Butler wrote a final report on the evidence found and testimony taken by the impeachment managers in their investigation.

Boynton was unhappy with Butler's handling of the impeachment managers' investigation, believing his pursuit of Woolley had been to the detriment of pursuing other guilty parties.

Cornelius Wendell gave a news interview that confirmed aspects of Boynton's reporting, and which accused Perry Fuller of offering Senator Ross several thousand dollars to influence his vote.