100NL - turned top pair facing weird line

[gjim]

Villain is 19/10/3.5 over 30some hands

Poker Stars - No Limit Hold'em Cash Game - $0.50/$1 Blinds - 6 Players - (LegoPoker Hand History Converter)

SB: $99.00
BB: $94.05
UTG: $143.35
MP: $383.95
CO: $83.15
Hero (BTN): $130.85

Preflop: Hero is dealt K[img]/images/graemlins/heart.gif[/img] J[img]/images/graemlins/club.gif[/img] (6 Players)
3 folds, <font color="red">Hero raises to $4.00</font>, SB folds, BB calls $3.00

Flop: ($8.50) 9[img]/images/graemlins/diamond.gif[/img] 7[img]/images/graemlins/spade.gif[/img] 6[img]/images/graemlins/club.gif[/img] (2 Players)
BB checks, <font color="red">Hero bets $6.00</font>, BB calls $6.00

Turn: ($20.50) K[img]/images/graemlins/club.gif[/img] (2 Players)
<font color="red">BB bets $12.00</font>, Hero calls $12.00

River: ($44.50) A[img]/images/graemlins/heart.gif[/img] (2 Players)
<font color="red">BB bets all-in for $72.05</font>

When he calls my bet on the flop I figure his range has sets, combo draws, 2 pair, a random pair or 88 in it. If hes paid attention to how much I cbet he could have A high or two overs too, but I dont know hes been at the table long enough to realize.

I hit top pair on the turn but his lead here really confuses me. I have no idea what this bet means. Maybe the K hit him, maybe he has a big hand and he doesnt want me to check behind, or he picked up a club draw or something. I called for pot control, but is there an argument for raising here? I tend to find that flop leads are probing type bets, but this turn lead confused me.

Do I call the river here--88, 78, 98, 68 all missed. River overbets tend to be hella stronger than 1 pair though.

I think I was behind here, but I have no idea cause his line is confusing.