Jan Tchoryk, 55, was one of two Chicago firefighters killed in-the-line-of-duty this week.
Tchoryk's cousin said she had just had dinner with him and his wife in the days and hours before his death.
The veteran Chicago fire lieutenant collapsed on the 11th floor of a Gold Coast high-rise Wednesday morning as a fire was raging in an apartment on the 27th floor.
READ MORE: Chicago high-rise cited for inspection violations before deadly Gold Coast fire
Tchoryk died of hypertensive-arteriosclerotic cardiovascular disease, which translates to a heart attack due to natural causes, according to autopsy results released by the Cook County medical examiner Thursday.
Tchoryk's family is remembering him as the happiest kind of guy.
"He was always the connector," cousin Tanya Adams said. "He was always the friendly person in the room. He was always smiling. I mean he brought joy to everyone that met him."
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Adams said she'd just enjoyed a long dinner and phone calls with Tchoryk and his wife, Natalia, in the days and hours before his death.
"He was always concerned about everyone else and never concerned about himself - ever," Adams said. "He was very selfless."
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Fire officials said the fire was caused by combustibles being too close to a heat-generating appliance.
Tchoryk, who was on-duty for Ladder 10, was one of two Chicago firefighters killed in-the-line-of-duty this week.
Firefighter Jermaine Pelt died of smoke inhalation Tuesday while fighting a fire on the city's Far South Side.
Tchoryk's body was transported from the medical examiner to Cumberland Chapels in the village of Norridge, northwest of the city, Friday morning.
Chicago Fire Department Ambulance 66, surrounded by a police motorcade, transported his body.
Chopper7HD showed firefighters and fire trucks staged on bridges over Interstate 290 as the motorcade passed.
Body of CFD firefighter taken from morgue to funeral home
Some were standing and saluting.
Services were announced for Tchoryk Friday.
Visitation will be held from 3 to 9 p.m. Wednesday at Cumberland Chapels, and the service will take place at 10 a.m. Thursday at St. Joseph Ukrainian Church. Internment will immediately follow.
Pelt's body was transported to Blake Lamb Funeral Home Friday afternoon.
Procession for Chicago firefighter killed in South Side fire
Pelt had walked his daughter down the aisle at her wedding days before his death.
Those he left behind include a 6-year-old son.
Those who knew him said he was a soft-spoken leader who found a way to make a connection with everyone.
Funeral arrangements for Pelt have not been released yet.
The Chicago Fire Department's EMWQ Retirees', Widows' & Children's Fund is supporting the families of the fallen firefighters. To donate, visit www.widowsandchildren.org. A public fundraiser is also being planned at Leona's Pizzeria & Restaurant, 3877 N. Elston, on F April 21.