Questionable work, poor oversight and lack of training have weakened background checks for federal employees and contractors, according to a recent report from the Office of Personnel Management’s inspector general.

Federal auditors determined that OPM, which oversees U.S. government background checks, must strengthen its controls over the firms that conduct screenings.

Concerns about federal background checks increased last year after former National Security Agency contractor Edward Snowden leaked sensitive information about the government’s electronic surveillance programs and Navy contractor Aaron Alexis killed 12 people in the Washington Navy Yard shooting.

The Pentagon determined that the government missed opportunities to restrict Alexis’s access to military installations, despite warning signs that he was mentally unstable.

The Justice Department filed a lawsuit in January saying that the support-services firm USIS, which handled most of the government’s background checks, filed more than 660,000 cases without properly reviewing them.

Lawmakers have criticized OPM for allowing its contractors to review their own screenings.

In a statement on Thursday, Sen. Claire McCaskill (D-Mo.), who heads the Senate Subcommittee on Financial and Contracting Oversight, described improper background checks as “nothing short of a threat to our national security.” She said the government needs to tighten its controls over the system.

OPM Director Katherine Archuleta said in a statement Thursday that “I remain deeply committed to ensuring the integrity and efficacy of our program and products, which is why OPM has enacted a number of reforms in the months since the cases analyzed in this audit were processed.”

OPM announced in February that it would no longer allow contractors to review their own background checks and that it would rely on its own employees to do the work.

The agency also said it has established an internal team to audit contractors’ performance, in addition to increasing the number of inspections it performs and implementing an automated tracking tool to ensure that reviewers meet investigative standards before closing cases.

The inspector general’s analysis looked at the processes OPM and its contractors used for reviewing background checks and recommended how to improve the system.

USIS declined to comment on the audit Thursday.

Below are some highlights from the report, which was released June 4.

●USIS claimed to be working impossibly fast

The report said at least two USIS employees completed an “abnormally high number” of reviews in a short time frame, noting that one worker finished more than 15,000 reviews in a month, with many occurring within minutes of each other.

The inspector general found that OPM was aware of abnormal reviews from one of the USIS employees and that the agency took administrative action against that person.

●Weak controls

Auditors found some cases in which background checks were not reviewed at all, saying that “it is clear to us that the contractors are not conducting a pre-review of all investigative items as required by the OPM contract.”

The report noted problems with the processing system that allowed cases to move forward without proper reviews. For instance, the system would indicate that a background investigation had been checked for quality simply because an employee had logged on to research it.

Auditors recommended that OPM require its contractors to mark cases specifically as “review complete” to signal that a review actually occurred.

●Training issues

OPM said its contracts going forward will require background-check firms to provide documentation of their training records within one day of a request for the materials.

The agency also said it would ask the firms to reevaluate their internal controls to show that reviewers have completed mandatory training.

Josh Hicks