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John "Jack" Leonard Kocourek

April 30, 1944 ~ August 25, 2023 (age 79) 79 Years Old
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John Leonard “Jack” Kocourek, age 79, of Manitowoc and Pigeon Lake, died at Holy Family Froedtert Hospital under Sharon Richardson Hospice Care in the early morning hours of August 25, 2023.

John was born on April 30, 1944, in Manitowoc, the first child of Leonard and Evelyn (O’Neil) Kocourek. As a child he studied the accordion and became quite accomplished playing the instrument, by the age of 6 he played often with the Romy Gosz Orchestra and live on WOMT radio. He attended St. Boniface grade school, graduating with the Class of 1958, and Lincoln High School, serving as the treasurer of the Class of 1962. Jack led the funding installation of the carillon in Lincoln’s tower. His class continued to maintain and update that carillon over the years. He delighted in chairing his class reunions as well. In 1965, he along with his buddy, Bill Frieder enlisted in the US Air Force. Following basic training he was stationed at KI Sawyer Air Force Base in Gwinn, MI and subsequently at Strategic Air Command Headquarters at Offutt Air Force Base near Omaha, NE. He was honorably discharged in 1969. That same year he earned a Bachelor of Science Degree in Business Administration from Bellevue College in Bellevue, NE.

Jack began working for Burroughs Corp. after college and continued throughout their merger with Sperry to form Unisys. He led the installation of main frame computers in banks throughout the U.S.

On April 19, 1990, he suffered a major hemorrhagic stroke while waiting to board a plane from Detroit to Los Angeles. It left him completely paralyzed on his left side. With great determination, spunk, and hard work, Jack led an active life for the past 31 years.

On July 3, 1991, he married Mary Jo (Herrmann) Sieracki, moving back to Manitowoc permanently. He became active in the community; he served on the Board of Directors of the Capital Civic Center where his pet projects were the creation and installation of seating for the handicapped in the theater and converting the marquee to digital signage.

For years after returning to Wisconsin he served on the DNR Committee whose purpose it is to make the outdoors accessible to the handicapped. Being active as a wilderness camper prior to his stroke, this service was so important to him. Jack was a Packer season ticket holder and so enjoyed attending home games, assisted by his good friend Bob Staudinger.

He cherished the memories of times spent at the Pigeon Lake cottage with friends and family, especially with the grandchildren as they were growing up. Jack and Mary Jo enjoyed traveling the US and even made two trips to South America making good friends in Argentina.

Jack was a member of the Manitowoc Yacht Club, Elks, St. Thomas Newton, Pigeon Lake Association, and the Capital Civic Center. He loved playing cards, especially Cribbage and Sheepshead, and continued his work with computers.

He is survived by his wife of 32 years, Mary Jo Kocourek; children: Dr. Erin (Dan) Bannink, and Matthew J. Kocourek (Amber); sisters: Pat (Paul) Neuser, and Nancy Garceau; brother-in-law and best friend: Dick Herrmann; stepchildren: Rob (Debra) Sieracki, Jamie (Deb) Sieracki, Rick Sieracki, Amy (Tom) Schmidt; step grandchildren: Trevor Sieracki, Kinsey (Jacob) Gonzales, Shelby Sieracki, Chase Sieracki, Carrie (Roy) Bratz, Kyle (Eliane) Sieracki, Cody (Ersy) Sieracki, Kendra (Matthew) Johnson, Sharaya Schmidt, Cheyenne Schmidt; eight step great grandchildren, nieces, nephews, the mother of his children: Joyce Kocourek, other relatives and friends. He was preceded in death by his parents: Leonard and Evelyn Kocourek; brothers-in-law and sisters-in-law: Bill Garceau, George and Corrin Herrmann, Cindy Herrmann; and nephew: Christopher Herrmann

Funeral Services will be held at 12:00 pm (Noon) on Saturday, September 16, 2023, at St. Thomas the Apostle Catholic Church, 8100 Brunner Rd, Newton. Rev. David Beaudry will celebrate the Mass of Christian Burial. Military Honors will be accorded after the service by Vietnam Veterans Chapter #731 of Manitowoc. Family and friends may call at the church on Saturday from 10:00 am until the time of service at 12:00 pm- Noon. Burial of his cremated remains will take place on Monday, September 18, 2023, at 10:00 am at Calvary Cemetery, Manitowoc.

The Lakeshore Family Funeral Homes, Pfeffer location is assisting the family. Online condolences may be expressed by visiting

Loving and generous by nature, remember Jack with a donation to the charity of your choice or St. Thomas the Apostle Catholic Community, Newton; Capital Civic Center; Camp Sinawa or The Crossing of Manitowoc County.

Thank you to all of Jack’s faithful visitors over the last 15 months. Your love and support made his days much brighter.

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September 16, 2023

10:00 AM to 12:00 PM
St. Thomas the Apostle Catholic Community
8100 Brunner Road
Newton, WI 53063

Funeral Service
September 16, 2023

12:00 PM
St. Thomas the Apostle Catholic Church
8100 Brunner Road
Newton, WI 53063

September 18, 2023

10:00 AM
Calvary Cemetery
2601 South 14th Street
Manitowoc, WI 54220


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