“First your house burns up and then a chopper goes down — that’s some pretty bad mojo you carry around,” Luis told Danny, who does not have the best relationship with the cartel.
Donnie Wahlberg, who portrays Danny on the show, also hinted there is more to Linda’s death. “Linda’s been gone, and nobody really thought, ‘Hey, maybe there’s more to this than we thought,'” he told Parade. “It wasn’t until Luis Delgado came along that he raised the possibility that, ‘You poked the bear, and there are consequences to be paid for that.’ He didn’t quite say it in that way, but I think we may discover that the burning down of the house was not the end of it. That Danny did provoke revenge.”
At the time of Linda’s death, actress Amy Carlson, expressed some disappointment about the way she was written off the show. “I feel badly that she dies the way she dies,” she said at the time. “I did not know they would do that, I was surprised. I wouldn’t have done that.”
So, this could be a way to give fans the closure they wanted.
Source : https://www.distractify.com/p/who-killed-linda-blue-bloods