Madonna's family is in mourning.

The singer's brother Anthony Ciccone died at age 66 on Feb. 24, according to an Instagram tribute from Joe Henry, who is married to Madonna's sister Melanie Ciccone. 

"My brother-in-law, Anthony Gerard Ciccone, exited this earthly plane last evening," Joe shared on Feb. 25. "I've known him since I was 15, in the spring of our lives in Michigan so many years now gone."

Posting a black-and-white photo of Anthony, Joe continued, "As brother Dave Henry (who took this photograph) notes here, Anthony was a complex character; and god knows: we tangled in moments, as true brothers can. But I loved him, and understood him better than I was sometimes willing to let on."

Noting that "trouble fades," the singer and songwriter said that "family remains— with hands reached across the table." 

Madonna, 64, has yet to speak out on social media about her brother's passing, and his cause of death has not been shared. 

Family friend Debi Mazar also left a heartfelt message following his death. 

"I have such fond memories of time spent with Anthony back in the late 80's. A real Renaissance Man," the Entourage actress wrote on Instagram Feb. 26. "Full of prose, lover of literature, his Italian Heritage, good wine & cooking. He would drive his 1960's Cadillac over to my Brooklyn apartment in a snow storm, bring a pot of his freshly prepared Ragu, and all the fixin's, and we would cook & laugh and talk all night."

She said she respected her "brilliant" friend, who "nurtured my young soul," adding, "I will always choose to remember his kindness & smile." 

Madonna, Anthony and their siblings grew up in Detroit, Michigan but lost their mother to breast cancer in 1963 when they were kids. 

Her passing greatly affected their family, with Madonna telling Rolling Stone in 1989, "If she were alive, I would be someone else. I would be a completely different person. I have to be careful sometimes. When someone dies and the years go by, you tend to make them into something they're not."

Joe also touched on the tragedy in his "farewell" message to Anthony on Feb. 25.

"I want to think the god your blessed mother (and mine) believed in has her there, waiting to receive you," he wrote. "At least for today, no one shall dissuade me from this vision."