By Nicole Chavez, CNN

(CNN) -- Details about the deadly bombings in Austin remain scarce, but one thing is clear, experts say: whoever made the bomb knew what they were doing.

Three parcel bombs exploded at homes in the Texas capital over 10 days, killing two people, wounding two others and leaving a community shaken.

As state and federal agencies work together to find answers, here's what experts say the explosions tell us about the culprit or culprits.

These are not their first bombs

Making a bomb that works at the right time is harder than it might sound.

All of the explosives in Austin detonated while a victim was carrying them, and not while the suspect or suspects was placing them on the victims' doorsteps.

"That shows that the person who's doing this, they know what they are doing and they've probably practiced a lot," Ben West, a security analyst with the geopolitical intelligence platform Stratfor, told CNN affiliate KXAN.

It often takes several attempts for parcel bombers to "hit their stride," and they "are rarely this effective" on the first try, a report released by Stratfor said.

These are the victims of the Austin package bombings

The bombmaker could be from Austin

Or the suspect is working with someone who does live in the Austin area.

The packages were not delivered by the US Postal Service or any other mail delivery service, so someone hand-delivered them, likely overnight, to the three Austin homes, the Stratfor report says.

Authorities are likely looking at surveillance video from neighbors' yards that may have captured any vehicles or people going to and from the area, said Ryan J. Morris, founder of Tripwire Operations Group, a company that provides explosives training to law enforcement.

What we know about the Austin explosions

Suspect is a skilled bombmaker

Not many details about the construction of the bombs have been made public, but Austin Police Chief Brian Manley said "these are very powerful devices."

"So there's a certain level of skill and sophistication that whoever is doing this has, and ... we are hoping to use the evidence we have to track them down based on what we are seeing on all three scenes that seem to be consistent," Manley told KXAN on Tuesday.

The way the bombs were detonated could indicate how skilled the maker is.

"The detonation of the device when it was moved could indicate the use of a remote detonator," the Stratfor report said, or the use of a triggering device such as a mercury switch -- which is activated by movement.

If the bomb maker used a remote, it would have "required the bomber to have had visual contact with his victim -- potentially exposing him to detection," the Stratfor report said.