COLUMBIA, IL ( KPLR ) - Investigators with the Major Case Squad say they may extend their customary 5 day working period as they continue looking for the killer of three people in Columbia, Illinois Tuesday.

Officers confirm they have traveled out of state to interview someone they believe can give them important information that might lead to an arrest.

Meanwhile, visitation is Friday afternoon for the victims of a triple murder in Columbia, Illinois. 31-year-old Sheri Coleman and her two sons, 9-year-old Gavin and 11-year-old Garett were found dead inside their home Tuesday morning. Visitation services for the victims begin at 4 p.m. Friday at the Grace Church in Chester, Illinois.

Sunday night a Community Candlelight Vigil for Sheri, Garett and Gavin Coleman is planned. The vigil will be held in Bolm-Schuhkraft Memorial City Park near the tennis courts. There will be brief service at 8:00 pm followed by time for the community to come together in remembrance of the lives of Sheri, Garett and Gavin Coleman. Everyone is encouraged to bring their own candles.

Police are not releasing many details on the case, but sources tell News 11 detectives are looking to speak with someone outside the St. Louis area who may have information.

Officers also spent a good deal of time searching a stretch of Interstate 255 just on the Illinois side of the Jefferson Barracks Bridge on Thursday.

Sheri's husband, Chris Coleman, was at a south county gym early Tuesday morning and asked police to check on his family after he couldn't reach them.