The number was untraceable - almost.

On Election Night in 2010, The Baltimore Sun's switchboard lit up with reports of a suspicious "robocall": it told voters to relax, that President Obama and Gov.Martin O'Malley had been successful, and that there was nothing left to do but wait for the results. Those who called us said they believed the call was a trick to keep Democratic voters home, and one person provided the number from their caller ID.

Naturally, The Sun wanted to know who was behind the call; Democrats including Mayor Stephanie Rawlings-Blake immediately had tried to pin it on former Gov. Robert L. Ehrlich Jr.'s campaign, but his camp vehemently denied it and the Republican party was calling for an investigation. Some speculated that it was actually the Democrats, trying to make voters think Republicans were attempting to suppress their vote.

The Sun was eventually able to pinpoint the election consultants behind it; the state prosecutor's office later filed criminal charges. Julius Henson is on trial this week, and Paul Schurick, campaign manager for Ehrlich, was convicted of four charges in the matter last year.

Here's how the story came together:

The first attempts to track the number, which had a DC area code, were not immediately successful; when it was dialed, the caller received a dial tone, and database and search engines turned up nothing. A reporter even paid a few bucks for two online services that claimed to be able to trace any number, but struck out there as well. [Side note: Be wary of such services!]

When a reporter searched Google for web sites containing the number, there were a few hits - in the form of complaints on various web sites about past unsolicited election robocalls. The complaints came from around the country, and seemed to indicate the calls came from Democratic candidates.

People reported unsolicited calls from the number regarding school board elections in Tallahassee, Fla., a candidate for mayor in Gadsden, Ala., the Democratic incumbent governor in Tennessee, a Democratic candidate for the New York state senate, and even someone purporting to be poet Maya Angelou. Another said they heard a voice that said he was a "lifelong Republican," but didn't elaborate on what the message was, and another said the call they received was about a "person hosting a town meeting for Democrats."

The issue then was finding one of the candidates who had facilitated a call using this service. If they could say, or if The Sun could discern through campaign finance records, who they had paid for their robodials, a reporter could identify callers and press them further.

Finally, a breakthrough came in a nonpartisan mayoral candidate from Gadsden, Ala., who referred The Sun to his campaign manager, a consultant from Birmingham who worked with Democrats. He said he had used a service called Robodial.org, because of its low rates. In addition, though the New York state senate candidate didn't immediately return my call, she had an expenditure for Robodial.org in her campaign finance reports.

The theory about a reverse-psychology move by Democrats was gaining steam. In addition to the Democratic consultant from Birmingham and the Democratic New York candidate, Robodial.org's website explicitly said the company worked only with progressive and Democratic causes and candidates, and would not work with Republicans.

The Sun sent an e-mail to Mark Hampton, the owner of Robodial.org, and told him that while he wanted to help Democrats exclusively, his service appeared to have been used to try to keep Democrats home. He was disturbed, and quickly got back to The Sun after checking his records.

He said the calls - more than 50,000 of them, he said at the time - were paid for by a woman named Rhonda Russell, who was previously political director for the liberal group Progressive Maryland. He also said she had been a longtime customer.

Were the Democrats behind the call after all?

"The consultant who set up that call has been using our system for a couple of years, and in the past we understood that her calls were in support of Democratic candidates," Hampton told The Sun in an e-mail. "Apparently something has changed."

But she had listed herself for purposes of the call as an employee of a firm called Universal Elections, and a reporter immediately went to the campaign finance database to see who had given money to that firm.

It was Ehrlich's campaign that had directed more than $97,000 to two companies affiliated with Henson – Politics Today and Universal Elections.

The Sun couldn't reach Henson immediately, but posted a story online. And Henson later in the day held an impromptu news conference outside his home in which he admitted that he was behind the calls.

He said the intent was to motivate Republican voters, but records showed the calls went out to Democratic households. Soon after, he would be criminally charged, along with Ehrlich aide Schurick.