DENVER (AP) — Denver police say there were 96 homicides in the city last year, the highest number recorded since 1981.

The Denver Post reports the number of killings spiked in 2020 when police recorded 95 homicides, up from 63 homicides in 2019.

The number of homicides has trended upward since 2014, when the city had a record-low 31 killings. Denver had 100 homicides in 1981, the highest recorded for the city.

Criminologists point to a variety of possible factors for the increase in violence, including stress brought on by the pandemic, fallout from the 2020 police protests, a worsening drug-use epidemic and the continuous influx of guns into communities.