When Spanish garment maker David Mayor arrived in Bangladesh a decade ago the fashion label he set up had the motto "clothing with a heart".

In an industry notorious for harsh working conditions he said he wanted to show it was possible to run an ethical business in which workers were trained well and treated with respect.

The story of how that dream ended in the rubble of Rana Plaza, an eight-storey factory complex that collapsed in April killing 1,129 people in one of the world's worst industrial accidents, is a cautionary tale for global retailers now scrambling to prevent another fatal accident in Bangladesh.

Rana Plaza was built on swampy ground, with substandard concrete. It was designed as a five-storey shopping center, but the owner of the building, a local political leader, rented it out to factory owners and built three more floors.

"David tried to do something good, better than the locals, but finally he was overtaken," said Brother Massimo Cattaneo, a Roman Catholic missionary who runs a technical school in northern Bangladesh and worked with Mayor on a training programme he funded there.

Despite repeated attempts in Spain and Bangladesh, Reuters was unable to contact Mayor for comment. He has made no public statements since the accident and it was not possible to establish whether he has hired a lawyer.

Mayor had nothing to do with the construction of Rana Plaza. But as the part-owner of a factory in the building the Spaniard, who was not in Bangladesh at the time, is one of those named as under investigation in the police case launched after the disaster. He has not been arrested.

All the other factory owners named by police, including his partner, are now in custody while the police complete their investigation. Although none have been charged, a government panel has recommended they face charges of culpable homicide, which carries a maximum life sentence.

Interviews with former employees, clients and associates of Mayor show he invested in workers and appears to have been popular with his staff. But some staff also said that conditions in the factory gradually deteriorated as the company began to focus on winning larger orders.

ETHICAL CREDENTIALS

Bangladesh's garment industry employs some 4 million people, mostly women. While the jobs give the women economic power and an independence they did not have before, many work long hours in poorly ventilated, fire-trap factories.

At first, Mayor thought he could change that, negotiating with buyers for longer deadlines to avoid excessive overtime, according to people who worked with him. He set up a fashion label, Tacsocial, that advertised its ethical credentials with the "heart" slogan and motif.

In 2007, aged 29, he started another clothing firm, Phantom TAC Ltd, a joint venture with local partner Aminul Islam, documents seen by Reuters show.

"Workers' conditions are not bad, but we want to improve them further," Mayor told Dhaka's Daily Star in 2008. A few weeks later Phantom TAC opened the factory at Rana Plaza, in an industrial suburb of Dhaka.

Brother Cattaneo said the factory seemed safe, and several workers interviewed by Reuters said at the start things were better than in many factories.

"Our wages were paid on time every month, and we left work by seven or eight at night. The behaviour of the bosses was good at the beginning," said Rashida Begum, who crawled out of the ruined building. She is now unemployed, suffers chest pain and is scared to go back to a factory.

"HEALTHY CONDITIONS"

One of Mayor's steadiest clients was Spanish catalogue-sales company Cristian Lay, which worked with Phantom TAC from 2007 to 2012 and helped fund Cattaneo's rural training programme aimed at the poor, rural women who flock to Dhaka in search of work.

Domingo Gonzalez, head of quality control for Cristian Lay, said he had visited the factory frequently and was impressed.

"It was a totally normal factory with healthy conditions, with a lot of light," Gonzalez said. Other clients over the years included Inditex, owner of Zara, and Spanish department store El Corte Ingles, a former Phantom-TAC official said.

In the Daily Star article, Mayor said he'd worked out he would have to charge an extra 10 cents per piece to really improve lives. His fashion label was meant to make that possible and he wanted to venture into retail, opening a boutique in a wealthy Dhaka neighbourhood.

"When you are a manufacturer negotiating orders with buyers that 10 cents becomes very important, it is very competitive and 10 cents becomes a lot," he said. "However when you look at 10 cents on a retail price, it is nothing."

At the beginning, Mayor lived in Dhaka's diplomatic zone and came to the factory most days, two former employees said. He spoke a smattering of Bengali and called his staff "brother", which was well received.

But about a year after the Rana Plaza factory opened he moved back to Spain to focus on marketing, travelling to Bangladesh every few weeks with new clients, several employees said.

That, some workers said, is when the problems began.

The reason for the change is not clear, but a deteriorating economy in Europe, his principal market, almost certainly made it harder for Mayor to develop a dream of more ethical fashion. Eventually the "heart" boutique closed. A plan to massively expand the training projects was dropped, Cattaneo said.

Instead Phantom TAC began to focus on large export deals.

In the days before the disaster, it was working flat out to complete a sample order for Spanish retailer Mango in the hope it would lead to a bigger, lucrative supply contract with the company, one of the world's top buyers.

Mango, which has over 2,600 outlets in 107 countries, said it had not finalised the order found in the rubble. The company, based in Barcelona, said that it would have gone ahead only had a trial sample been found to be up to standard and had Phantom TAC passed Mango's checks on its labour practices and safety.

Under pressure to meet mounting orders, line managers drove staff harder, sometimes making them work through the night, some workers said. Reuters was not able to speak to any line managers from the company.

The increasing tensions on the factory floor were kept from Mayor, 20-year-old seamstress Runi Akhter said.

"When he came there was an announcement by loudspeaker," said single mother Akhter, speaking in the two-room house she shares with eight people, including her parents and two young children. "We were told by the managers that if we complained to him we'd lose our jobs."

"ARE THEY ALL DEAD?"

On the morning of April 24, managers ordered staff into work at the five factories in Rana Plaza, even though the building had been evacuated the day before after a crack appeared in a pillar.

Minutes after they sat down the power went out in the building and heavy generators on the upper floors kicked in with a shudder. The building shook hard and crashed to the ground.

Amarat Hossain, a merchandiser who had worked for Mayor since 2007 coordinating with buyers, said he was late to work that day, and by the time he arrived Rana Plaza had collapsed into a mound of broken concrete.

As he frantically tried to contact colleagues his mobile phone rang. It was his boss, asking why he couldn't reach Phantom TAC chairman Islam.

When Hossain told him the news he said Mayor broke down, screaming "oh God, oh God", into the phone and asking: "Are they all dead?"

Industry officials said some 200 workers and managers died at Phantom TAC, with dozens more severely injured. Reuters spoke to several survivors.

All the workers spoken to remembered Mayor as a benevolent figure, who always had a kind word and was opposed to forced overtime. Two said he had touched their heads -- a sign of respectful affection in Bangladesh.

But labour activist Babul Akhter said he believed Mayor could have found out about the worsening conditions from factory log books that document the hours being clocked.

"Instead of touching the heads of workers, he should have looked at the documents, the service books," said Akhter.

UNDER INVESTIGATION

Mayor was last seen in Bangladesh in March. Two people who know Mayor, and the Bangladesh consulate in Barcelona, said he was in Spain, but Reuters was unable to locate him.

The registered phone number in Spain for Phantom TAC now belongs to another company. He did not respond to messages left at, or letters mailed to, his registered business address in the northern Spanish town of Reus.

Bangladesh has not contacted the Spanish embassy in Dhaka to request information about his whereabouts. It has not requested an Interpol notice for Mayor.

"Since he is a foreigner we are careful so that he is not charged wrongly ... but his name is in the primary accused lists," said the officer in charge of the case, Bijoy Kumar Kar of the Criminal Investigation Department.

Speaking on condition of anonymity another Bangladeshi policeman and a Spanish government official, both with knowledge of the case, said they believed Dhaka did not plan to seek Mayor's arrest due to worries of scaring off foreign investment.

Mainuddin Khandaker, a senior home ministry official, said a decision on whether to charge Mayor would be taken based on the evidence, not the impact on foreign investment.

"But before putting his name on the charge sheet definitely all evidence will be examined and investigated thoroughly to identify his level of negligence and also to avoid sending a wrong message across the world," he said.

The merchandiser Hossain said he had spoken to Mayor "three or four times" by telephone since the accident.

"He said his next step is prove he was in no way involved in this whole process, because he didn't know anything about the crack. He was very upset," he said.