The program, long criticized by advocacy groups and members of Congress concerned about oversight, permits law enforcement to take possession of cash and property seized during investigations. More than $6 billion in forfeited funds has been shared with state and local law enforcement since fiscal year 2000, and over $4 billion has been returned to crime victims during that same period, according to the report from the department’s inspector general.

The report said the department does not collect adequate data to determine whether law enforcement seizures of funds truly benefit criminal investigations or the extent to which they infringe on civil liberties.

The inspector general’s office reviewed 100 cash seizure investigations involving the Drug Enforcement Administration but said the DEA could verify that only 44 had advanced or been related to ongoing investigations, resulted in the development of new investigations or led to arrests or prosecutions.

“When seizure and administrative forfeitures do not ultimately advance an investigation or prosecution, law enforcement creates the appearance, and risks the reality, that it is more interested in seizing and forfeiting cash than advancing an investigation or prosecution,” the inspector general’s office wrote.

The report also said the department does not require its local task force officers to be trained on asset forfeiture laws before participating in federal forfeiture, leading to the perception of inconsistent and arbitrary operations.

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In a written response to the report, the Justice Department’s criminal division said the inspector general had relied on incomplete or flawed data during its investigation and had presented misleading conclusions. It said the 100 DEA investigations discussed in the report represent a “very limited aspect” of the department’s overall asset forfeiture operations.

It also said the report had overlooked the “robust training” the department already provides on asset forfeiture law, practices and policy, and that the inspector general had underreported the return of seized funds to their owners.

The report is the latest instance of scrutiny of the government’s criminal and civil asset forfeiture efforts. The Justice Department sees the program, in which law enforcement can assume title to property seized during investigations, as a way to strip suspects of the proceeds of their activities, to deter crime and to compensate crime victims.

Former Attorney General Eric Holder in 2015 tightened control on the department’s asset forfeiture operations amid concerns that property could be seized without judicial oversight and without the owner ever being charged with a crime. That policy restricted the ability of the federal government to take possession of, or adopt, assets seized by local authorities.

Republican Rep. Bob Goodlatte of Virginia, who is the House Judiciary Committee chairman and has been critical of asset forfeiture operations, called on the Justice Department to implement the inspector general’s recommendations.

“Today’s report by the Inspector General makes it clear that asset forfeiture is in desperate need of reform,” Goodlatte said in a statement. “While asset forfeiture is a useful law enforcement tool to fight crime, the current lack of oversight and training poses dangers to Americans’ civil liberties.”