What next? The secret service role

■ The US Secret Service takes special measures to screen the mail of the public figures it protects.

■ Each piece of mail undergoes screening before delivery for potential hazardous substances or devices.

■ Suspicious packages are routinely quarantined for further examination at facilities that include a chemical and biological laboratory and a forensics laboratory.

■ “The packages [sent this week] were immediately identified during routine mail screening procedures as potential explosive devices and were appropriately handled as such,” the Secret Service said in a statement.

■ While the investigation is in its earliest stages, the recovery of three of the devices and the envelopes that contained them could potentially provide federal agents with a treaure trove of leads and evidence. It could allow them to assess the sophistication of and care taken by the person or persons who built and mailed the bombs.

■ Bomb technicians will likely seek to defuse the devices and try to determine where their components were purchased or where the bombs were made.

■ Evidence technicians will try and recover possible traces of DNA and fingerprints from the components and the envelopes that contained the bombs.

■ Federal agents with the US Postal Inspection Service will likely play an important role in the investigation, examining the postage and postmarks and any handwriting. Once they determine where the packages were mailed from, they will examine surveillance video at post offices and around blue letter boxes where the packages may have been deposited.