50NL Top Set / Tough River Spot

[22pajo]

$0.25/$0.50 NL Hold'em Cash Game, 10 Players

SB: $10.60
BB: $9.50
UTG: $19.62
UTG+1: $48.50
Hero (UTG+2): $97.60
MP1: $24.10
MP2: $49.70
MP3: $84.06
CO: $9.08
BTN: $29.25

Pre-Flop: K[img]/images/graemlins/club.gif[/img]K[img]/images/graemlins/heart.gif[/img] dealt to Hero (UTG+2)
<font color="red"> Hero raises $2.00</font>, 2 folds, MP3 calls $2.00, 4 folds

<font color="blue"> No great reads on villain other than he cold called a couple of my open raises only to fold to flop c-bets </font>

Flop: ($4.75) 9[img]/images/graemlins/club.gif[/img] K[img]/images/graemlins/diamond.gif[/img] J[img]/images/graemlins/heart.gif[/img] (2 Players)
<font color="red"> Hero bets $3.00</font>, MP3 calls $3.00

Turn: ($10.75) 7[img]/images/graemlins/club.gif[/img] (2 Players)
<font color="red"> Hero bets $15.50</font>, MP3 calls $15.50

River: ($41.75) 4[img]/images/graemlins/spade.gif[/img] (2 Players)
<font color="red"> Hero bets $30</font>, <font color="red"> MP3 raises $60</font>, Hero?

I'm pretty sure i'm beat on the river as villain has called every bet of mine for 3 streets before this. I'm hoping he he flopped a set of 9's or 2 pair with KJ and is "slowplaying" them. Of course QT is possible here.
Who lays this down and why?