Each of three homemade bombs discovered on buildings in Provo and Orem this year, including one that damaged an LDS chapel Sunday, has been more refined than the previous one.

That has police concerned because "we're fairly confident it's the same person," said Provo Police Capt. Duane Fraser."We are concerned that he's building confidence and expertise to some anticipated target in the future," he said. Police found two unexploded bombs attached to buildings in Orem and Provo in January and February.

The latest target was an LDS church in northwest Provo. No one has been injured in the three incidents. "He doesn't appear to be targeting people," Fraser said.

While Provo and Orem police and the Utah County Sheriff's Department believe the incidents are linked, they have yet to figure out a motive.

"You don't know what their intent is, unfortunately. We wish we did," said Orem Police spokesman Gerald Nielsen.

Circumstances surrounding the three bombing incidents have been strikingly similar.

Early Sunday morning, a bomb taped to a window of the Grandview Stake's 1st, 5th and 9th Wards chapel, 1555 N. 1350 West, Provo, exploded, spraying glass into the building and parking lot. Nearby residents told police they heard an explosion about 4 a.m. Damage was estimated at $2,000 to $3,000.

On Feb. 17, a custodian spotted a ticking object with wires coming out of it taped to a window at Provo's Wasatch Mental Health office, 286 S. 800 East. Police deactivated the device, causing a slight explosion and about $300 damage to the window. The bomb was found on a Sunday. Police said it had been on the building since the preceding Saturday or longer.

An unexploded bomb was found Jan. 28 on the ground below a window at the Orem City Library. The 3-by-5-inch device had apparently been attached to the window but fell to the ground. Police discovered the bomb on a Monday. Nielson said investigators don't know how long it had been there.

Provo police said components of each of the three homemade devices were similar. Fraser said they were constructed with readily available materials. All three were equipped with timers.

There have apparently been no witnesses to any of the incidents.

The federal Bureau of Tobacco, Alcohol and Firearms is investigating all three incidents. Police have yet to receive analyses of the bombs from the federal agency.