The NYPD has known for years its Special Victims Division didn’t have enough resources to adequately investigate sex crimes involving adults — yet department leaders failed to act.

That’s according to a scathing report the city Department of Investigation released today following a year-long probe.

Among the more damning findings: NYPD Commissioner James O’Neill misled the public about the department’s efforts to tackle an increase in rape reports. In December, O’Neill told reporters the department added seasoned detectives to handle the extra caseload, which has coincided with the growth of the #MeToo movement. But the DOI found NYPD staffing for adult sex crime investigations has remained almost flat.

“If you judge an agency's priorities by where they place their budget and resources, then adult sex crimes — and in particular things like acquaintance rape — are not a priority,” DOI Commissioner Mark Peters said.

The NYPD released a statement disputing some of the report's findings, including staffing and caseload figures. The NYPD also said DOI didn't interview key officials like the Chief of Detectives.

According to the DOI report, the NYPD failed to follow through on a 2010 working group recommendation that the department add 40 percent more detectives to the Special Victims Division including more senior and experienced investigators. Staffing levels remained flat while caseloads are up 65 percent since 2009, according to the DOI report.

DOI found there are only 67 investigators for more than 5,000 adult sex crime cases a year. That’s compared to about 100 homicide detectives to handle less than 300 murders a year. As a result the department has prioritized so-called “stranger” rape cases, while “acquaintance” rape cases have gotten less attention, the report says.

The Special Victim Division also has antiquated facilities and inadequate training. Motorcycle patrol cops get six to eight weeks of specialized training, while sex crime detectives get five days, according to the report.

The NYPD released a statement blasting the DOI report.

“This document is an investigation in name only; it is inaccurate, misleading and does material damage to the relationships of trust the NYPD Special Victims Division (SVD) has worked hard to develop with survivors of sex crimes,” the statement said.