This month marks the second time Seattle police made mass arrests around Third Avenue and Pine Street.

The first attempt in 2015 was an effort to end the open air drug markets and other criminal activity plaguing the surrounding area. It worked — for a while.

But what happened?

In early July, police were back — 42 people were arrested. This came two years after an effort called “9.5 Blocks” when sidewalks were altered, bus stops were moved, and an office for a multi-jurisdictional team was set up on Second Avenue. But between April 2015 and July 2017, crime returned to the area that cops cleared out.

RELATED: Seattle’s 9.5 Blocks effort to clean up downtown crime

“No matter where you are in the city, you can’t just arrest a number of people in one location and think you are done,” said Seattle Detective Mark Jamieson. “That doesn’t mean it is the end of the criminal activity. It will have an impact, and it’s going to send a message and slow down activity for a time. But over time, criminal activity may come back to the area.”

The stretch around Third Avenue and Pine Street recently became a problem again. It was an open-air drug market, Jamieson said. Investigations began. Undercover drug purchases were made. Of the more than 60 suspected drug dealers police investigated, 42 were arrested; 16 of those dealers had narcotics on them. An ounce of heroin, a half ounce of meth, and $10,000 were seized.

“If you spend any time downtown you will see a number of bike officers down there,” Jamieson said. “They were seeing activity pick up … we decided it was time. It had been about two years since we had done a concerted effort. It was time. A plan was put together.”

9.5 Blocks

The 2015 9.5 Blocks effort was launched by the mayor’s office. It was largely around Westlake Park, along First and Fourth Avenues and Stewart and Union streets — an area that is known for drug dealing, violence, and crime. People working in nearby office buildings call stretches like Third Avenue between Pike and Pine “Stab Alley.”

The city narrowed the sidewalks in the area in 2015, limiting the space to linger. Bus stops were moved a block away and newspaper boxes were removed so they could not act as tables for drug deals. An office was opened on Second Avenue for a multi-jurisdictional team to regularly meet and discuss crime.

Seattle police mostly swept away the crime with the mass arrests — an operation that cost roughly $1 million.

“That was very successful at the time, back in April of 2015,” Jamieson said. “They spent a number of months, a multi-jurisdictional operation. They spent a lot of time going after people dealing in drugs and other types of crime in that particular area around Westlake. At the end of the operation, they ended up arresting close to 100 people.”

There was a 30 percent reduction in overall crime within the weeks that followed; 45 percent drop in narcotics-related calls; and calls about suspicious circumstances dropped from 414 to 293.

9.5 Blocks Part II: Back to Stab Alley

According to the mayor’s office, the city’s multi-jurisdictional office on Second Avenue and Pike Street stayed open for a while. Meetings were held there between police, prosecutors, and others.

In the two years since 9.5 Blocks, city personnel related to the effort were reassigned to other parts of the city. As the crime rates went down, so did the frequency of meetings. They eventually stopped. The sidewalks that were narrowed eventually opened up. Bike cops continued to patrol the area and watched the blocks slowly return to the old ways.

“After there’s a number of people arrested, they go to jail, they are off the streets for a period of time,” Jamieson said. “But, eventually, those individuals get out of jail. Hopefully, they don’t go back to their old ways. But experience tells us that probably a number of them will. When those individuals get out of custody, chances are they may go back to that area and may try to do business again.”

Which means that despite the recent mass arrests that took suspected drug dealers off the streets, the job still isn’t over for Seattle police.

“We will be watching, and we will be monitoring the area,” Jamieson said.

“…and we rely on the public to let us know when activity is picking back up,” he said. “Then we will do another operation like this.”