Video from several surveillance cameras showed the man, wearing a baseball cap and a wig with glass beads, approach the armored SUV of former minister Fernando Londono and then flee, getting on the back of a motorcycle driven by another man.
The video shown by RCN TV does not show the man actually place the bomb, presumed to have magnets, on the door of Londono's vehicle. Officials said it was detonated by remote control.
A police report says the man was bleeding from an arm when a taxi driver picked him up 10 blocks from the scene of Tuesday's attack,
It says the man told the cabbie, "Get me out of here," but the driver refused because of the blood. Authorities released three composite sketches of the man Wednesday based on witness descriptions.
The government has not ascribed blame for the bombing, although Colombia's main leftist rebel group, the Revolutionary Armed Forces of Colombia, or FARC, has committed bombings in the past.
Defense Minister Juan Carlos Pinzon said Wednesday that neither the FARC nor any other group had been ruled out in the case. He said the United States and Britain were assisting Colombia in the investigation of the blast, including the type of bomb used.
The midday attack has raised fears of a return to the sort of violence not seen in the Colombian capital in years.
Londono, an archconservative 68-year-old radio host and newspaper columnist, had glass shards removed from his chest and was out of danger, authorities said.
It was the first fatal bombing of an apparently political nature in the capital in nearly a decade. It traumatized a city that two decades earlier was ravaged by car bombs set off by drug traffickers fighting extradition to the United States.
President Juan Manuel Santos has announced a $277,000 reward for information leading to those responsible. Santos said Londono had received death threats in the past and had about 19 bodyguards.
A critic of the FARC, Londono was interior and justice minister in 2002-2003 under President Alvaro Uribe. He hosts a daily radio show called "The Hour of Truth" and firmly opposes peace talks with the FARC, calling the rebels terrorists and murderers.
He has also been critical of Santos for allegedly being soft on the rebels, who have stepped up attacks in recent months.
Analyst Leon Valencia of the Nuevo Arco Iris think tank said the FARC was capable of Tuesday's attack, but said groups from the extreme right opposed to peace talks proposed by the FARC should not be ruled out.
"The object of the authors of the attack wasn't just the ex-minister but the destruction of whatever possibility of reconciliation," Bogota Mayor Gustavo Petro tweeted on Wednesday.
Leftist congressman and human rights activist Ivan Cepeda said he feared the attack could trigger other acts of violence, including targeting the left.
"I see a clear intent to destabilize," Cepeda said, blaming "sectors who don't want peace."
The FARC last month released what it said were its last "political prisoners," 10 police officers and soldiers held for as many as 14 years. But it continues to inflict casualties on security forces in ambushes and hit-and-run attacks and authorities blamed it for two bombings in February in provincial towns that claimed the lives of 16 people.
The FARC currently holds a French journalist who was accompanying security forces on a drug lab-destroying mission when rebels detained him two weeks ago. The FARC said on Sunday that it intends to free him soon.