Police experts expected to wrap up their investigation at the bombing sites near Dawson Creek, B.C., on Monday. (CBC)

Police are no longer trying to find a truck seen near the site of last week's second gas-pipeline bombing near Dawson Creek, B.C.

RCMP in northern B.C. were looking for a full-sized pickup truck earlier Monday after several hunters reported seeing a truck around 6 a.m. on Thursday, just hours after a blast damaged an EnCana sour-gas pipeline east of Dawson Creek.

RCMP spokesman Sgt. Tim Shields said investigators have analyzed and compared the reports with the known facts surrounding the incident.

"As such, the sighting of this truck has now been eliminated as part of the investigation and investigators are no longer looking for assistance from the public to find it," Shields said.

RCMP also ruled out farmer Wiebo Ludwig, who was convicted of vandalizing oil and gas wells in Alberta in the late 1990s and spent almost two years in prison, as a suspect in the pipeline bombing.

Shields confirmed media reports that investigators had spoken to Ludwig, but "he is not a suspect in this investigation."

Investigation at sites wrapping up

Meanwhile, explosives experts and other investigators were wrapping up their work at the blast sites, after seizing a number of exhibits from the second location.

RCMP Sgt. Tim Shields says investigators continue to follow up on leads that have been provided by the public. (CBC)

"Investigators are continuing to follow up on leads that have been provided by the public," Shields said on Monday.

"Some of these tips have proved to be very helpful and investigators would like to thank the public and the media for their help with solving this crime."

No arrests have been made.

A threatening letter sent to local media before the blasts complained about the oil and gas industry.

The first explosion targeted a sour-gas pipeline in a remote rural area south of Dawson Creek sometime overnight Oct. 11-12, but the blast did not significantly damage the pipe.

The second explosion, overnight Oct. 15-16, caused a small leak in another sour-gas pipeline about 20 kilometres from the first.

Many area residents have expressed concerns about the possible health effects from the highly poisonous sour gas.