Charlotte-Mecklenburg police arrested two 15-year-old boys on charges of murder in connection with the death of Zachary Joseph Finch, a college baseball player who was killed while trying to buy a cellphone he found using an online sales app.

The teens were arrested Thursday and Friday and sent to a juvenile detention center. CMPD withheld the suspects’ names because of their ages.

Finch, 21, who pitched for Kentucky’s University of the Cumberlands, was killed just before 1:30 p.m. on June 18 in the 2300 block of Farmer Street in southwest Charlotte. Officers arrived to find him lying on the ground in the front yard of an apartment. Paramedics pronounced him dead at the scene.

According to CMPD, Finch had gone to the location looking to buy a cellphone, which had been advertised through an online application called letgo. Police said Finch did not know the people he was meeting.

Investigators believe the motive was robbery.

As a result of the killing, Charlotte-Mecklenburg Police announced they are creating “safe exchange areas” where Charlotte residents can handle sales made via internet apps, according to the Charlotte Observer. Those sites will be announced as early as this week, the Observer said, citing CMPD spokesman Rob Tufano.

Finch’s death happened at a time when Charlotte is experiencing a spike in violent crime, especially homicides. CMPD so far this year has investigated 50 killings. That compares with 68 homicides in all of 2016, which was up from 60 the previous year.

Unlike the Finch killing, at least 36 of the city’s homicides this year have occurred between people who knew one another, authorities said.

Meanwhile, police are cautioning residents against meeting strangers in unsafe location to buy products found online.

“If they’re concerned about their public safety, do not make that transaction,” said CMPD Capt. Chris Dozier. “It’s up to the person to make the transaction on their terms.”