Investigators in the United States probing the assassination of a senior Hamas official have drawn links between U.S. companies and suspects in the case, bringing them closer to identifying them, according to an American press report Saturday.

The findings show U.S. authorities playing a great role in the probe than previously revealed, the Wall Street Journal reported.

Mohammed al-Mabhouh, a senior Hamas official accused by Israel of planning a series of terror attacks and weapons transfers, was found dead in a Dubai hotel room on January 19.

Dubai police have publicly accused Israel's Mossad spy agency of the hit, which sparked diplomatic outrage when it emerged that a group of suspects used forged passports of Israeli allies to enter the Gulf emirate.

The U.S. companies identified by investigators include wed-based firms that pair freelance job-seekers with employers and transfer payments between them, the Journal said. Authorities have identified financial transfers from several intermediary businesses into prepaid, cash-card accounts used by suspects in the Dubai killing, according to international investigators.

The companies are not accused of any complicity in the attack — instead, investigators believe suspects might have posed as freelancers to obtain while that obscuring its source, using the money for operational expenses, such as plane tickets.

Representatives of several companies identified in the probe, including, Elance Inc. and Rent a Coder, now called vWorker.com, said they had not been contacted by U.S. authorities and were unaware of any investigation.

Earlier in July a suspected Mossad agent charged with involvement in providing a forged German passport for the assassins began a fight against his extradition to Germany from Poland.

Uri Brodsky—who is also known to investigators by other names—asked a Polish court to send him to Israel instead of extraditing him to Germany.

On July 7, a district court ordered his extradition to Germany on the forgery charges only, meaning that he could only be tried in Germany for forgery and not spying—sparing Israel a potentially embarrassing high-profile espionage trial.

But Israel could face fresh discomfort if its key ally, the U.S., draws a new link between the killing of Mabhouh and the Mossad.