(CBS) NORTON SHORES, Mich. - Authorities investigating the disappearance of Jessica Heeringa, a 25-year-old Michigan mother who vanished last Friday from the Norton Shores, Mich. gas station where she worked, are now combing an area around a nearby park where there were reports of gun shots heard last weekend, CBS Detroit reports.
Officials are working to determine whether or not the shots reportedly heard near P.J. Hoffmaster State Park in Norton Shores are connected to Heeringa's abduction.
The young mother disappeared Friday, April 26 around 11 p.m., shortly before she was set to close the gas station. The station didn't have a security camera and there were no signs of a struggle or robbery, though police are treating the case as an abduction.
A man trying to buy gas called police at around 11:15 p.m. that night after finding the gas station open but no employees around.
Investigators have reportedly received dozen of tips since Heeringa's disappearance and have released surveillance footage captured from a tavern about a mile from the gas station which shows a gray- or silver-colored minivan traveling away from the scene of the alleged abduction.
Norton Shores Police Chief Dan Shaw told MLive that authorities believe the minivan caught on the surveillance video is the same vehicle described as being at the Exxon station at the time of Heeringa's abduction.
According to CBS Detroit, a man was questioned by police Wednesday night after being pulled over in a silver minivan that fit the description of the vehicle authorities were focusing on. That man was reportedly released Thursday morning and has not been charged.
Police say they have also interviewed and cleared at least four other people, the station reports.
Anyone who may have witnessed suspicious activity near the Exxon Mobil gas station in Norton Shores, Mich. is asked to contact Silent Observer at 231-72-CRIME (231-722-7463) or call 911.