The Cats, who collected their second walk-off win of the season, are now 36-11-1, while BYU fell to 24-20 with the loss.
K-State held a comfortable five-run lead through seven innings, but a four-run Cougar eighth and back-to-back solo-home runs in the ninth tied the game at eight apiece before the Wildcats went in order in the bottom half to send the game to extras.
Thomas Rooke (5-1), who entered the game after the solo homers and effectively shut down BYU, worked around a two-out single in the 10th to get the K-State offense back to the plate.
Jason King recorded a one-out walk against BYU reliever Jordan Muir (0-2) to start off the 10th inning and then moved to second base on a sacrifice bunt by Drew Biery.
Cruz, who doubled in his previous at bat, approached the plate and immediately fell behind 0-2. After fouling off a pitch, the senior stuck his bat out on an outside pitch and punched it down the left-field line, just out of the reach of Cougar left fielder Sean McNaughton for the game-winner.
"It was nice to see a senior help us get that school record," head coach Brad Hill said. "It (school record) is done and over. Congratulations to these guys for how hard they've worked and the consistent play they've had all year long, but now it's time to move on and extend that."
Cruz, Carter Jurica and Nick Martini collected two hits apiece, while Martini drove in a team-high two runs.
Rooke recorded his fifth win of the season after two scoreless innings, allowing two hits and striking out two.
The Wildcats received a great outing from senior starter Todd Vogel, who allowed two runs on five hits. The right-hander tied a season high with five innings pitched and tallied a season-best five strikeouts.
Three different BYU hitters – Kent Walton, Michael Bowen and Kasey Ko – recorded three hits and two RBI apiece.
BYU cracked the scoreboard first when the first two batters of the game singled off of Vogel, putting runners on first and third. Walton was next and hit a RBI groundout to short to put the Cougars up 1-0.
Following a scoreless second, Kansas State took the lead with three runs in the third inning. Dane Yelovich recorded a one-out walk and, after a strikeout, Jurica hammered a 0-2 pitch off the right center-field wall for a RBI triple, his second of the season.
Martini followed with a double down the left-field line, scoring Jurica, to give the Cats a 2-1 lead. Justin Bloxom was next and struck out, but the ball bounced away from BYU catcher Chad Nacapoy. The catcher picked up the ball and attempted to throw Bloxom out at first, but the throw went down the right-field line, allowing Martini to score from second.
Ko pulled BYU to within a run in the top of the fifth with a one-out solo homer over the wall in deep center field.
The Cats quickly put up another three spot in the bottom half of the inning when a Yelovich walk, an Adam Muenster double and consecutive sacrifice flies from Martini and Bloxom gave K-State a 6-2 advantage.
Kansas State tacked on another run in the seventh when Martini singled through the right side and moved first to third on a Bloxom double down the left-field line. King drove Martini home on a sacrifice fly that was caught against the left-field wall, pushing K-State out to its five-run lead.
That extra run would become important as the Cougars plated four runs in the eighth inning off reliever James Allen to get within one. McNaughton doubled and came around to score on a Walton triple. Steve Parker was next and hit another extra-base hit, a bloop double into left to plate Parker and knock Allen out of the game.
Evan Marshall entered and forced a groundout for the second out of the frame but surrendered a two-run homer to Bowen over the wall in left center-field.
Kansas State scored an insurance run in the eighth when Cruz ripped a leadoff double into left and scored when Rob Vaughn singled through the right side of the infield.
That run also proved to be valuable as BYU received consecutive solo-home runs from Ko and Nacapoy to tie the game at eight apiece and sent the game into extra innings.
Kansas State concludes its two-game conference series against BYU on Tuesday at Tointon Family Stadium. First pitch on Tuesday is set for 6:30 p.m., with a special Cinco de Mayo celebration prior to the game. The special-edition tailgate begins at 5 p.m., beyond the left-field wall with $2 Coronas, while supplies last. It's also a Quarter Hot Dog Night and a "T-Shirt Tuesday" as the first 150 fans into the stadium will receive a free t-shirt.