On Christmas Eve 2008 he went to the parking lot of the HSBC processing center in Sioux Falls, shot his wife, and then turned the gun on himself.
Now, the tragic day when Steven and Julie Tassler died is being replayed in front of the South Dakota Supreme Court, because Julie's estate believes HSBC should pay out worker's compensation to the Tassler children.
Attorneys for the estate say the murder-suicide in the parking lot of HSBC in Sioux Falls would have never happened if she wasn't at work.
"Julie especially during those times was never away from the children except while she was at work," attorney for the estate Dean Nasser said.
Julie was known to take mid-morning smoke breaks inside her car in the parking lot. Nasser says this was the only time Steven knew he could confront Julie without the kids around. And because HSBC required her to work that day they should pay out a worker's compensation claim to the Tassler's surviving children.
"Julie's work provided the only access, the only isolated access to Julie before cooling off and that access would not have existed but for the constraints of her employment," Nasser said.
But, attorneys for HSBC say paying out worker's comp for domestic cases that spill over into the workplace would open the floodgates for claims.
"Every domestic assault would be work related and would be compensable because the only connection you have to show is that the employee had to be at work," HSBC attorney Eric DeNure said.
Attorneys for HSBC also argued that Tassler was not required to be in the parking lot at that time on that break and that's why they should not have to pay the worker's comp.
The justices will make their decision on the case at a later date.