American musician Tito Jackson has died at the age of 70. The Jackson 5 founding member and older brother of Michael Jackson passed away on Sunday, September 15, from a suspected heart attack while driving from New Mexico to Oklahoma, according to family friend and former Jackson family manager Steve Manning.

The official cause of death has not yet been determined. Tito was last seen on September 9 in Munich, Germany, just six days before his death, as he prepared for a performance with The Jacksons, featuring his brothers Jackie and Marlon.

He is survived by his three sons, Taj, 41, Taryll, 39, and TJ, 46, as well as nine grandchildren. Tito’s former wife, Delores ‘Dee Dee’ Martes, whom he married in 1972 and divorced in 1988, was found dead in a swimming pool in 1994; her death, initially ruled accidental, led to her boyfriend Donald Bohana’s conviction for second-degree murder.

The Jackson 5, which included Tito, Jackie, and Jermaine as founding members, was later joined by younger brothers Marlon and Michael.