Jim Daniels was a detective investigating the theft of the Sword of Beowulf, when he was attacked by the thief, Harm. It is unknown whether he survived the attack.
Background in other media
In the comics, Captain Jim Daniels was a detective of NYPD's 12th Precinct. He was a supporting character in Man-Bat's stories in Batman Family (1975–1978). He was slightly older than his portrayal in Young Justice, and had a big moustache.