– After the deadliest year in two decades, the first half of 2017 seemed just as grim in Chicago as homicides remained devastatingly high, raising fears that the spike in violence had become a new normal for the city.

In the second half of the year, homicides plummeted, contributing to about a 15 percent overall drop in killings compared to 2016.

That decrease has raised new hopes that Chicago could make progress in shedding its national reputation for gun violence, an image fueled by both President Donald Trump's frequent mentions and by the distressing losses on Chicago's streets.

Police Superintendent Eddie Johnson cited new technology and tactics in crime-plagued neighborhoods for the decline, and suggested that police relations with the community were improving. Anti-police sentiments were inflamed in 2016 after the release of a video showing a white police officer fatally shoot black teenager Laquan McDonald. Johnson said he believed the video and its publicity emboldened criminals to break the law, a brazenness he now believes may have waned.

"I think that they used that to their advantage because if you think they don't pay attention to that type of thing, you're fooling yourself because they do," he said. "I think the boldness of them is starting to tick down a bit, but it's still there."

Two key measures of police aggressiveness — arrests and street stops — are around the same level this year as last, and yet homicides dropped. The Police Department notes, however, that while overall arrests are flat, arrests for gun crimes increased 28 percent.

Experts and some neighborhood activists warn that tallies in 2017 aren't reason to cheer just yet. Though violence has dropped in recent months, Chicago will still end 2017 with historically high totals. Indeed, if last year was excluded, this year's homicide toll would be the highest in Chicago since 2002.

In 2016, Chicago logged more than 700 homicides. This year's totals will be below that tally. Through Tuesday, 644 people were slain in Chicago, compared with 754 during the same period last year, a drop of about 15 percent. That represents the largest single-year drop in homicides since 2004.