AUSTIN, Texas -- The investigation into the three package bombings that occurred within 10 days continues.

Two people in in the community were killed and three were injured, and the bomb maker is still at-large. Some experts say the suspect is no amateur. 

The first package exploded on March 2 and claimed the life of 39-year-old Anthony Stephan House. Security expert Fred Burton anticipated another was imminent. 

“Bomb makers rarely make just a few, they tend to keep going down that path until they’re either killed or captured,” said Burton, who is the vice president of intelligence for Stratfor.

Stratfor is the Austin-based firm is a geopolitical intelligence platform that offers analysis. 

Federal and local authorities are searching for the suspect or suspects who sent a trio of packages to separate residences in Austin.

The explosions killed two, including a teenage boy, and injured others, while raising fears that a professional is on the loose. 

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“The thing that strikes me with this bomb maker is that one, he got it right," Burton said. "There’s a lot of trial and error with bomb making, and I know first hand from that. So, he has practiced or he has been experienced in this field.”

Bombs usually have a unique signature. Explosive devices actually leave a viable amount of forensic evidence, like fragments of shrapnel, pieces of battery or wire. Burton said he believes this bomb had a mercury switch. 

“If your viewers can envision a thermometer, so when you pick it up, and then it’s turned over that thermometer will set off the firing train to cause the device to explode,” said Burton. 

Investigators aren not rejecting any possibilities, looking at the people and the patterns. 

“In the bomb makers mind, there is a specific reason and a method to his madness," Burton said. "We don’t know the answer to that question yet.”