Blood and skin found on the Sarai Sierra, the Staten Island mother murdered on her trip to Turkey last month -- have been linked to a homeless man presumably on the run for the Syrian border, now a key suspect in the case.

Detectives investigating Sierra's killing have launched a nationwide manhunt for this suspect, known as Ziya T., according to The New York Daily News.

"Our security forces are intensively conducting searches outside of Istanbul; when he is found, clear answers will emerge," Istanbul Gov. Hüseyin Avni Mutlu told The Hurriyet Daily News.

Sierra had disappeared on Jan. 21 during her solo two-week Istanbul vacation. Authorities found her broken body 11 days later near the city's ancient walls along a costal highway. She was killed with a brick blow to the head - and later suspect Ziya T. was caught on city cameras selling Sierra's jacket in a secondhand bazaar after the murder, Turkish police told The Hurriyet Daily News.

A witness told The New York Daily News that he spotted Ziya T. on the day Sierra went missing, close to the location where her body was discovered.

"There were marks, like nail scratches, on both sides of his face. When I asked what they were, he said he had fallen in the underbrush and that his face got scratched," the witness, Mahmut G., told police, according to the Dogan News Agency of Turkey.

Ziya T., who tended to spend time near the ancient walls in Istanbul's Cankurtaran neighborhood, fled Istanbul.

Police realized he was a suspect when they went to his family's home in Karabuk, about 200 miles east of Istanbul, where they took a hair sample from his pillow there. The cops also gathered DNA samples from his two brothers and sister, The Daily News reported.

Detectives are saying that Ziya T. may have made way for Hatay, about 500 miles south of Istanbul, near the Syrian border, The New York Daily News reported.