A 44-year-old high school principal from New Jersey has died after complications following donating bone marrow to a complete stranger.

Here's what we know

When he heard about a 14-year-old boy in France who needed a bone marrow transplant, Westfield High School Principal Derrick Nelson knew he had to help.

But his sleep apnea presented a problem. His doctors worried about how that medical condition would affect Nelson's reaction to anesthesia. Nelson was also a carrier for sickle cell anemia, which prevented doctors from harvesting stem cells. Without these two options, doctors decided to use a local anesthetic rather than a general anesthetic to operate.

Despite the setbacks, Nelson wasn't discouraged. "If it's just a little bit of pain for a little bit of time that can give someone years of joy, it's all worth it," he told the school newspaper at Westfield High School in February.

"He was the type of guy to take the shirt off his back and give it to you," his father, Willie Nelson (not the singer), told NJ.com. "He was very good at everything he did. He gave 100 percent of his life to education."

But during the procedure at Hackensack University Medical Center in February, something went wrong. Nelson slipped into a coma and never woke up. He died on Sunday.

"We really don't know the full story of what happened," his 81-year-old father said. "We were expecting him to come out of the coma he was in. But he didn't make it."

Nelson was engaged and has a 6-year-old daughter.

In a Facebook post, Westfield Mayor Shelley Brindle called Nelson's death "a tremendous loss for our community," but said that she was sure "his legacy will live on in the generations of students whose lives he touched.

Nelson had also served for more than 20 years in the Army Reserve and had re-enlisted, according to KYW-TV.