“I don't believe a new investigation is necessary," Johnson told the Florida newspaper.
Rep. Jackie Speier (D-Calif.) called on the Pentagon to reopen the investigation this week, saying that it failed to look into private emails between Allen and Kelley. She said the inspector general should have subpoenaed Allen’s private emails when he did not turn them over.
"The fact that they didn't even pursue accessing the private emails is very disturbing to me," Speier said in an interview with USA Today. "Because it would suggest that it was an incomplete investigation at the very least. At the worst: [they were] intentionally not pursuing an investigation into whether or not there was an inappropriate relationship, secrecy, national-security breaches. Classified information."
Bridget Serchak, a spokeswoman for the DOD inspector general, said in a statement that the investigation was “comprehensive and thorough.”
“We did not receive or uncover any indication of a breach of national security,” Serchak said. “During the OIG administrative investigation of allegations involving General Allen we were able address the specific allegations without issuing a subpoena.”
The investigation into Allen unfolded after his emails were caught in an FBI probe into former CIA Director David Petraeus, who resigned when the FBI investigation revealed an extramarital affair with his biographer, Paula Broadwell.
The FBI handed over roughly 25,000 pages of emails between Allen and Kelley, who had initially started the FBI probe when she got threatening emails from Broadwell.
Johnson, who went through the emails with another Pentagon attorney last year, said Wednesday that he didn’t think a subpoena would have uncovered any additional communication between Allen and Kelley.
"My strong recollection is that the emails that were handed over to me by the FBI were the product of subpoena, therefore they would have picked up every single communication between Mrs. Kelley and Gen. Allen," Johnson told the Tribune.
"They were very comprehensive and you could tell over a several year period that nothing was missing," said Johnson. "There didn't seem to be any gaps in what we were looking at."
Johnson would not discuss what was contained in the emails, which he said ballooned to 25,000 pages because the email histories included in each reply.
But he said that "my instinct was that the relationship did not go any further than the emails. There was nothing like, 'oh we had a great time last night.'"
When the investigation was first made public, Allen denied any wrongdoing. Both he and Kelley denied having an affair, which would have been a crime under the military’s judicial code.
Allen, whose nomination to a new post in Europe was delayed by the investigation, was cleared by the inspector general early this year.
He opted not to take the new position and instead retire from the military, citing his wife’s health.
Kelley last month sued the Pentagon and the FBI, accusing the government of violating her privacy by making her name public as part of the Petraeus investigation.