flopped trips against unknown. 50NL

Never seen this guy before and he just sat down. Seems to be a slightly loose time of day but the table is fairly tight overall. No idea if hes floating me or if he hit the FH or lower trips. I checked the turn to get another bet from a PP and lose a bet less to AJ/ FH. Howd I do? Raise the river?

Party Poker No-Limit Hold'em, $ BB (8 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

UTG ($69.27)
UTG+1 ($50.50)
MP1 ($50.95)
Hero ($48.25)
CO ($41.92)
Button ($70.54)
SB ($54)
BB ($29.50)

Preflop: Hero is MP2 with K, J. SB posts a blind of $0.25.
3 folds, Hero raises to $2, 3 folds, BB calls $1.50.

Flop: ($4.25) J, 3, J (2 players)
BB checks, Hero bets $3, BB calls $3.

Turn: ($10.25) A (2 players)
BB checks, Hero checks.

River: ($10.25) 5 (2 players)
BB bets $5, [color=#CC3333]Hero ...

Bet turn. Raise river to 15 probably fold to a shove.