The leftwing militant who blew himself up outside the US embassy in Ankara had once sought political asylum in Germany but the country's security services identified him as an extremist, according to a newspaper report.
An article due to appear in Monday's edition of the Sueddeutsche Zeitung said the bomber went to Germany after he was released from prison in Turkey in 2001.
Citing "security experts," the newspaper said he had appealed for political asylum. German authorities rejected the request because they determined he had not been politically persecuted.
A radical Turkish Marxist group, the Revolutionary People's Liberation Front (DHKP-C), claimed responsibility for Friday's bomb attack at the embassy, where a Turkish security guard was killed.
The group, which is fiercely anti-US and is blacklisted by Washington and the European Union as a terrorist organisation, identified the bomber as Alisan Sanli.
Turkish authorities has said he was previously jailed for his involvement in an attack on an Istanbul military compound in 1997.
Because of his connection to the group, German authorities told Sanli to quit the country, but he disappeared.
The authorities had not put him under surveillance because he was not thought to pose a threat, the newspaper reported.