Hartwell played in 16 games last season, finishing with nine tackles on special teams, recovering an onside kick against the Green Bay Packers.
After originally attending Wisconsin, Hartwell emerged as a Division I-AA All-American after transferring down in levels, winning the Buck Buchanan Award and was named Gateway Conference Defensive Player of the Year.
Hartwell led the nation as a senior with 192 tackles, including 122 solos, to go along with five sacks, four fumble recoveries, two forced fumbles and an interception.
In three years with the Leathernecks, Hartwell set career marks for tackles with 512 and solo tackles with 308 to go with 12 sacks.
He majored in special education and was born in Germany.
Here's a transcript of his interview with Ravens Insider:
Ravens Insider: "What was it like last season watching more than playing?"
Hartwell: "Definitely, it was hard on me, because I had been starting all my life. It was kind of frustrating, but it turned out all for the good. I learned a lot as a rookie. Now, it's my time to step in."
Ravens Insider: "What have you learned from being around Ray Lewis?"
Hartwell: "Who doesn't learn anything from Ray Lewis just from watching him? He definitely gave me a lot of pointers and sat down and talked to me about things."
Ravens Insider: "How would you describe your playing style?"
Hartwell: "Obviously, I'll run to the football, sideline to sideline, and give out a punishing tackle. I've got to be in a bad attitude when I hit someone. I want to bring the pain."
Ravens Insider: "Do you have to imagine something to anger you enough to get into that mindset to do some bodily harm, like a perceived slight?"
Hartwell: "Not really. More than anything I'm a happy guy, always laughing. When it's time to play, I click that switch. Even between plays, I might be laughing. At the snap of the ball, I'm coming for you."
Ravens Insider: "What are you listening to in your CD player now?
Hartwell: "I'm listening to a lot of different things. It depends on the mood I'm in. I listen to gospel, R&B, rap every now and then. I'm pretty versatile."
Ravens Insider: "Do you have a hobby besides running into fullbacks?"
Hartwell: "I play chess. That's my favorite. It's a good strategy game. You really have to think about your moves."
Ravens Insider: "What was it like growing up in Las Vegas?
Hartwell: "It was great. Honestly, I can say I've never been to any city like Las Vegas, and my family and friends are there. It's a wonderful place to me."
Ravens Insider: "What's your game of choice at the casinos?" Hartwell: "I'll play a little bit of everything, but I'm not a big gambler. I do it when my friends are in town and we'll go out to a hotel and play a little.
" I like to play blackjack. I never lose too much money because I don't play big. The most I ever won was about $250."