The New Orleans Police Department has reported an overall drop in crime in the city in the first three months of the year, despite dramatic increases in the number of rapes and murders.

In a report released Thursday, the NOPD said major crimes overall were down by 8.2 percent in the first quarter of 2015, compared with the first three months of 2014.

Reports of simple robbery and assault fell the most, down by 27.3 percent and 18 percent respectively.

The department confirmed, however, that murders climbed from 31 to 45 — a 45 percent increase that has left criminologists searching for an explanation.

Rapes also jumped by a startling 53 percent, though it is unclear how much of that increase might be attributable to an increase in reporting.

The NOPD’s Sex Crimes Unit has been under heavy scrutiny from a federal monitor since a report from city Inspector General Ed Quatrevaux blasted five detectives in the unit for mishandling sexual assault investigations.

Quatrevaux warned in February that rape totals in 2015 could double or even triple because of more accurate reporting, and that prediction seems to be partially borne out in the first-quarter numbers.

Sexual assault advocates have said in the past that rising rape statistics can often indicate a rise in victims’ willingness to report crimes.

“We continue to be encouraged that more survivors of sexual assault are coming forward to the NOPD, and we are committed to fully investigating these crimes and hunting down the perpetrators,” Police Superintendent Michael Harrison said in a news release.

Another factor could account for much of the reported increase in rapes, according to NOPD spokesman Tyler Gamble. In July, the FBI changed its crime-reporting statistics to include male-on-male rapes and other sexual batteries that would not previously have been reported as rape cases. Under the bureau’s new definition of rape, reports have risen in many jurisdictions across the country.

The changes in reporting guidelines accounted for 13 of the cases reported in the first quarter of 2015, shifting what would have been a 27.5 percent increase in rapes to a 53 percent jump.

Harrison also pointed to a “significant” 16 percent drop in overall crime compared with the last three months of 2014.

Criminologists generally favor year-over-year comparisons because of seasonal variations. But the quarterly shifts could offer some indication as to whether new deployment strategies Harrison has touted as an improvement over those employed under his predecessor, Ronal Serpas, are making a difference.