The president has argued that the recent caravans are a threat to national security.
"The city of Chicago lost a doctor, a pharmaceutical assistant and a police officer — all going about their day, all doing what they love."
“The evidence was absolutely mind-blowing to me," said the lead researcher.
Four people were found shot to death execution-style in the basement of a Southwest Philadelphia home on Monday.
"Downtown is a very populated area, and so to have multiple gunshots fired in an area like this is concerning."