There was no party at the frat house that night and no one had admitted drinking with Spady, Sigma Pi President Darren Pettapiece told ABC News affiliate KMGH-TV in Denver, adding that the frat's members have always been responsible when it comes to alcohol consumption and risk management.
Other members of Sigma Pi declined to comment on Spady's death.
The national fraternity has suspended the CSU chapter of Sigma Pi, meaning the residents can still live there but cannot hold any social activities, The Associated Press reported. The national executive director said the move was not intended as punishment or an indication that the chapter was seen as having done anything wrong.
"We're taking control. We want to make sure what's going on," Mark Briscoe, national executive director of Brentwood, Tenn.-based Sigma Pi, told the AP.
The Greek community on the CSU campus does not allow parties involving alcohol at fraternity and sorority houses. Parties with alcohol are allowed only in third-party locations, such as bars or hotels, and guest lists must be submitted to the Greek Life office, a school official said.
A fraternity member was giving his mother a house tour Sunday when they found Spady's fully clothed body in an empty sofa-filled lounge on the second floor. Witnesses said that there was no vomit near her body and no drug or alcohol paraphernalia around her.
Police estimated that Spady died Sunday morning, so she may have been in the empty room about 12 hours before they were called.
CSU officials are waiting for Fort Collins police to complete their investigation before deciding what action to take.
"The university will continue to work closely with Fort Collins police and will take appropriate action pending results of the investigation," said Linda Kuk, CSU vice president for student affairs. "[The] administration is very concerned about the situation and has sent counselors to help university students and families affected by this tragedy."
Spady's friends in Nebraska said she was an honor student, head varsity cheerleader, homecoming queen and senior class president before graduating from Beatrice High School in Beatrice, Neb., in 2003.
Family friend Nile Dragoo called Spady "bubbly, refreshing, a breath of fresh air," who would light up a room as soon as she walked in.
Her family and friends are suspicious of the circumstances surrounding her death and say it's unlike her to binge drink and go into a frat house by herself.
"This just doesn't seem like her at all," Adam Tatro, a friend from high school, told KMGH-TV. "Sam, she was a smart girl. If you knew her at all through high school, she wasn't getting in trouble. She wasn't out doing stupid things. She was an all-around nice girl. This was out of character."
Spady was a former member of the Chi Omega sorority, just down the street from Sigma Pi, and still had many friends in Sigma Pi, friends told KMGH.
She was majoring in business and came from a prominent family in Nebraska. Her father, Rick Spady, owns several businesses, including Spady-Runcie, a car dealership in Beatrice, a town of about 13,000 located about 40 miles south of Lincoln.
Friends told KMGH she had said she wanted to go to school at CSU so that she could get away from the small-town life she knew.
A neighbor said Spady's parents were vacationing out of state when they got word of their daughter's death and immediately headed to Fort Collins.
ABC News affiliate KMGH-TV in Denver contributed to this report.