July 20 (Bloomberg) -- The suicide bombers who killed nine people including themselves in two luxury Jakarta hotels were challenged by staff over their suspicious behavior minutes before detonating their devices, a security official said today.

The JW Marriott bomber exited an elevator wearing a backpack on his chest and pulling a luggage trolley and told guards he was delivering a case to his boss, said Alan Orlob, global head of security for Marriott International Inc.

The Ritz Carlton attacker told restaurant workers he was a resident in room 2701 of the hotel, which has only 26 floors, as he sat down to order breakfast, said Orlob.

“What can you do?” Orlob, a former deputy sheriff and U.S. Army special forces soldier, said in an interview in the Indonesian capital today. “He would have blown anyway. These guys have failsafe devices on the bombs and he would have killed the two security officers and anyone standing in the lobby.”

Luxury hotels are grappling with the need to provide ease of access and convenience for business people and boost security as terrorists increasingly target hotels. Police are still trying to determine how bombers got their devices past security measures, a spokesman said today.

Marriott International, the biggest U.S. hotel chain, is studying the use of X-ray machines, “sniffer” dogs and entry barriers after the July 17 attacks, Orlob said. The Jakarta Marriott moved its drop-off area to the street and installed a metal detector after an attack in 2003 that killed 12 people.

Delivery Method Unclear

It’s unclear whether the Ritz Carlton bomber used an underpass that connects the hotels to transport his device from the Marriott, Sulistyo Ishak, deputy spokesman for the Indonesian national police, told reporters today. The underpass is for staff use only, he said. Marriott International owns the JW Marriott and Ritz Carlton brands.

The bombers probably stayed in room 1808 of the Marriott, where police found and defused an unexploded bomb, national police spokesman Nanan Soekarna said July 17.

Indonesian police are focusing their investigations on the Southeast Asian terrorist group Jemaah Islamiyah because the explosives and methods used in the attacks match previous bombings blamed on the al-Qaeda-linked organization, Soekarna said yesterday.

Bomber Challenged

The security guards at the Jakarta Marriott, which has been on “threat condition red” since it opened in 2001, challenged the bomber when they saw him wearing the backpack on his chest, said Orlob.

The attacker continued to walk toward the room where CastleAsia, a business advisory company, was hosting a meeting with chief executive officers, when a third security guard confronted the man, said Orlob. The bomber blew himself up as soon as he walked into the room, he said.

Orlob was in Asia conducting routine security surveys of Marriott’s hotels when the attacks happened, he said.

“Security will be more empowered to do all sorts of checks,” said Martin Hughes, director at PT Business Risk Indonesia, who has been advising companies operating in the country on security for more than a decade. “But the trouble for managers of a venue is after months, years following such an event people start to complain ‘why do we have to have our car searched, why do we have to have our bag searched?’”

At the Ritz, the bomber went into the restaurant and asked to be seated. Since he hadn’t given a correct room number the Ritz employees asked for his name, to which the terrorist responded by saying he would pay cash, according to Orlob. He detonated his device as a waiter went to get him coffee, said Orlob, who surveyed the damage at both hotels immediately after the bombings.

Similar Evidence

The unexploded bomb and other evidence were similar to explosive devices found in Cilacap, Central Java, earlier this year, which were linked to fugitive alleged JI leader Noordin Mohammad Top, Soekarna said last week.

Jemaah Islamiyah is blamed for a 2002 bomb attack on the Indonesian island of Bali that killed 202 people, 88 of them Australians. It is also blamed for the 2003 bombing of the Jakarta Marriott, a bomb blast outside the Australian Embassy in Jakarta in 2004 that killed at least nine people and another attack in Bali in 2005 when three suicide bombers killed themselves and 20 other people.

To contact the reporter on this story: Arijit Ghosh at aghosh@bloomberg.net

Last Updated: July 20, 2009 06:25 EDT