Mike Carp and Greg Halman were best friends when they played for the Mariners. Halman was stabbed to death by his brother on Nov. 21, 2011. Carp keeps Halman's jersey in his locker at all times.

(Evan Drellich)

ST. PETERSBURG, Fla. — It's not unusual for a player to show up to a new team with some of his old club's gear. Maybe he'll have an equipment bag, a few shirts. Then, typically, that gear is phased out quickly.

Even now, with his Red Sox career well underway, Mike Carp still keeps a Mariners jersey in his locker.

Most of the time, the jersey is impossible to pick out. It's navy, and usually sandwiched between the rest of the usual: road and home uniforms, alternates, street clothes, what have you.

It just so happens that in St. Petersburg, where the Sox played the Rays in a three-game series that wraps Thursday, Carp hung the jersey all the way on the right side of his locker. The adjacent locker was empty, and there's a lattice-like, metal window of sorts in the visiting lockers at Tropicana Field.

Walk by, and through the metallic weaving you can see it very easily: "Halman, 56."

A couple of times this year, Red Sox teammates have asked about the jersey. Not as a suggestion that Carp was doing something wrong, just out of curiosity. Why does he have it?

The answer never need be long.

"I explain to 'em, 'Hey, I had a buddy, he passed away,'" Carp said. "'He was a close teammate, best friend of mine.'"

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Greg Halman and Carp were indeed best friends. Halman was stabbed to death at age 24 by his younger brother, Jason Halman, on Nov. 21, 2011, in Rotterdam, Netherlands. Jason it was determined had a psychiatric episode, and was released from prison in Amsterdam to undergo treatment last August.

A 6-foot-4 toolsy outfielder, Greg Halman played 44 games in the majors. He signed with the Mariners when he was just 16.

Halman hit two home runs in his major league career, both in 2011 with the Mariners. The first came as a late-inning replacement for Carp in the lineup, on June 15. The second was July 19, a three-run shot to left — against John Farrell's Blue Jays. Chone Figgins scored on that shot, and so did Carp.

"Even today his mom posted a picture on Facebook," Carp said in April. "So it's like every day, some sort of memory, some sort of thing saying — it's definitely heavy on my heart. He's a best friend, he's a teammate. It's hard to explain that. You spend every day with a guy and then all of a sudden he's not there, it's kind of hard to get over."

Carp, who turns 27 next month, walked out onto the field at Fenway Park earlier this season to pose for a picture holding Halman's jersey. "His mom's going to love this," Carp said, as he stood on the top step of the dugout, with Halman's jersey in front of the Green Monster.

Halman loved Fenway Park, even though he only got to play one game there — a game in which, of course, Carp hit a three-run homer, on July 22, 2011. Halman's athleticism was clear that night, when he robbed Jarrod Saltalamacchia on a deep fly to center. Halman had a bad jump, but was saved by his great closing speed.

Per Baseball America in 2010, Halman was the team's No. 8 prospect heading into the season that he made it to the bigs: "Halman's game is centered on quick-twitch athleticism. It lends him explosive power at the plate and long, graceful strides in center field, where he's a solid defender with a strong arm. Plus-plus power is attainable with his whip-like bat speed and strong forearms. Lean and long-limbed, Halman draws physical comparisons to Andre Dawson and Alfonso Soriano."

Seattle Mariners' Greg Halman, right, is congratulated by Mike Carp after a three-run home run against the Toronto Blue Jays during the second inning of a baseball game in Toronto on Tuesday, July 19, 2011. (AP Photo/The Canadian Press, Frank Gunn)

Carp's first season with the Mariners organization was 2009. The team that drafted him, the Mets, dealt Carp the prior offseason. Immediately, he and Halman clicked.

"I got traded over and our lockers were close to each other that first spring 2009, and just getting to know him," Carp said, "obviously talented. I would have never known he was from the Netherlands. I thought he was just a regular American. He didn't have an accent or anything. He spoke a bunch of languages.

"He's just one of those guys that's easy to get along with," Carp continued. "Get along with everybody. You see him and tattoos everywhere; big, strong, physical presence. You think, 'I might not be able to talk to that guy.' But he made it a point that he was going to come talk to you, and let you know who he was, and, 'Hey, if you need anything, I got you.'"

Halman's charisma pulled together a tight-knit group.

When Halman was killed, Carp was at home in California. Another Mariners prospect, third baseman Matt Mangini — who happened to be born in Springfield, Mass., and lived there until he was 10-years-old — got the news ahead of Carp.

The Mariners made Mangini the 52nd overall pick of the 2007, and he bonded with Halman right away, just as Carp did.

"They were the same way," Mangini said of Carp and Halman. "From the day they met, whether it was on the field, off the field, they were together. And you'd develop that relationship when you spend that amount of time with people. ... Just the comfort and the confidence that he gave people, it was contagious."

Mangini was the one who delivered the terrible news to Carp.

"To get that phone call in the middle of the night, I got a text message from Matt Mangini, who's on the East coast, so it's probably 3 or 4 in the morning my time, he had just gotten up," Carp said. "That was a tough morning for me. Just having to place a few phone calls myself and inform other teammates and friends, it's a hard thing to do."

Carp made sure he was there, in Amsterdam, when Halman was laid to rest. Four Mariners teammates made the half-day-long trip as well: Dan Cortes, Adam Moore, Mangini and another European player who came to the States, Italy's Alex Liddi.

The service was something out of a movie, Carp said. A drive through the Dutch countryside. Everyone who wasn't a part of the service wore hats in honor.

"I'm sitting there trying to write a speech in the middle of it," Carp remembered. "They wanted us to talk… we're looking out the window as we're in the funeral procession. As we're pulling up there's probably 1,000, 2,000 people outside wearing red hats. Just a sea of red hats."

Carp had t-shirts made up for all his Mariners teammates back home once spring training started the next year. But shirts and jerseys are not the only tributes.

On Carp's left biceps is a tattoo of a baseball encompassing a map, with a red star located on both the West coast and Amsterdam. Halman had the same tattoo. Just under Mangini's right elbow is Halman's favorite Bible verse, Joshua 1:9, which reads in part: "Be strong and courageous. Do not be frightened, and do not be dismayed."

Carp and Mangini both knew the Halman family. A lengthy story was written in ESPN The Magazine about Halman's death, a story that both Carp and Mangini disliked. But the details of what happened to Greg and Jason don't so much matter now — Greg is gone.

"I knew the brother well," Carp said. "The brother would come over to visit a few times. We spent a lot of time together, hang out after games, watching TV, listening to music, playing video games. He was part of our family too as a group. We all kind of stuck together. Even his dad came into town, his brother, we all went shopping, had lunch and dinner, we spent a good quality two weeks together. It was just crazy to know that he did that. Obviously, we knew stuff was going on, some psychological problems, some isusses, but nobody knew for certain what it was."

A forensic expert leaves a house where Seattle Mariners outfielder Greg Halman was found bleeding from a stab wound in the Jan Sonje street in Rotterdam, Netherlands, Monday, Nov. 21, 2011. The 24-year-old Dutch player Greg Halman was stabbed to death early Monday and his brother was arrested as a suspect, Dutch police said. (AP Photo/Bas Czerwinski)

Shortstop Xander Bogaerts, Boston's top prospect, is from the Netherlands. He talked with Carp about Halman, and Bogaerts knew who he was. This year's World Baseball Classic made Carp something of a Netherlands fan, when the team made it all the way to the semi-finals. "Imagine having (Greg) as one of their star center fielders?" Carp asked.

Mangini's moved on from the game, hurt by injuries. He's getting married soon. Carp's having a good season in a part-time bench role. Liddi's with Seattle's Triple-A team, Tacoma. Cortes is in the D-backs system, while Moore's with Kansas City.

Their lives are mostly separate now, but Halman remains a uniting factor. Mangini saw a picture Carp posted of Halman's jersey.

"It just gave me chills, man," Mangini said. "That's how Greg would want it, that's the way. He wants to be with us. He's probably looking down on all of us all the time, wishing us the best. I know him and Carp understood the grind the same way. Greg had a lot to do with that — seeing his jersey in his locker every day probably gives him that confidence and that swag he needs to go out and keep representing for him."

As Mangini points out, Carp's a West-coaster, Mangini an East-coaster and Halman was from a whole other contintent. But Halman made common ground easy to find. Carp and Mangini both stay in touch with Halman's family on Facebook, including his mother, Hanny Suidgeest.

On Saturday, the day before Mother's Day, Carp said his thoughts would be with Suidgeest. The day of the holiday, she wrote on Twitter, "Love Never Dies."

Not for her, and not for Carp.

"We spent so much time together," Carp said. "Very approachable. He'd come up to me and talk to me, 'Where you from? Oh, Long Beach? Oh man, I'm from the Netherlands.' Sharing stories, and trying to reflect on life in Europe and growing up playing baseball in Europe, going to the States, and him coming over at 16-years-old, signing, being over here. It's pretty amazing what he accomplished. He went from the bottom to the top. Who would have thought?"

Link: MLB.com's video archive of Greg Halman

Follow MassLive.com Red Sox beat writer @EvanDrellich on Twitter. He can be reached by email at evan.drellich@masslive.com.