Before he died, his former girlfriend claimed she was pregnant with his child.
A year after his death, the former girlfriend filed for his survivor benefits from the city.
His family says that's when they did a blood type comparison.
"Back then, the attorneys were able to obtain the blood samples of the baby, the mother, and of course Danny- didn't match up at all," Danny's father Patrick Boyle said.
The city rejected the survivor benefit claim.
But, the baby's mother, Patricia Rossa, appealed to the workers' compensation court and, ultimately, all the way to the state Supreme Court.
The workers' compensation judge concluded Danny was the father largely based on testimony from his former girlfriend and her family.
The Supreme Court later affirmed the workers' comp decision.
That baby girl, Ashley, is 21 years old now.
The Boyles say two years ago Ashley asked to meet with them.
"We were almost wishing because that is another grandchild," Patrick said.
They say Ashley then agreed to submit to a DNA test.
And that her swab was compared to a pair of teeth Danny had extracted when he was in high school.
That recent DNA report, they say, has ruled out Danny as the father.
"It was emotional to say the least. She was crying, we were crying," Patrick said.
The Boyles say they thought that was finally the end of it.
But Ashley continues to collect survivor benefits from the city, almost $300,000 so far.
And, we learned that Ashley's college tuition is being paid for by the Hero Scholarship Fund, which helps the children of fallen and disabled police and firefighters.
"Yeah, her father, Daniel Boyle, he was a slain police officer and he died," Ashley's mother Patricia Rossa said.
We asked Patricia if she applied for the fund on her daughter's behalf.
"Actually the lawyer applied for her behalf and she just automatically gets it," Patricia said.
Ashley and her mother still insist she's Danny's daughter, despite everything.
"No, there was no DNA test, nothing by my knowledge," Patricia said.
Ashley also says she never took a DNA test.
But the Boyles say they saved the swab in a lab packet with what appears to be Ashley's signature.
We went to the Hero Scholarship Fund to ask what criteria they used to award a scholarship to Ashley.
"It is my understanding that we have a birth certificate from a woman who is acknowledged as Officer Boyle's daughter," David Rohde of the Hero Scholarship Fund said.
But, they won't show us the birth certificate or Ashley's application.
And, Danny's family says the fund never checked with them.
Patrick Boyle says all this reopens a painful episode, but it's time to clear the air.
"The truth has to come out. If the truth comes out, everybody will know and we can finally put this to bed," Boyle said.
On one final note, the Boyle family has established a scholarship of its own in Danny's name. They say Ashley not only would have been first in line, but they would have paid her tuition out of their own pockets if she were truly Danny's daughter.