(REUTERS) On a recent evening in a Midwestern U.S. city, a middle-aged woman with bandaged arms and a missing thumb entered a crowded restaurant. Nearby, children colored with crayons. Waiters rushed by.

The maimed woman, Rafida Ahmed, scanned the room nervously. The Atlanta financial executive has been hiding since Islamic militants wielding machetes attacked her on Feb. 26 in her native Bangladesh.

During the assault, her husband - the Bangladeshi-American secular activist and blogger Avijit Roy - was hacked to death. Ahmed sustained four head wounds, and her left thumb was sliced off. On May 3, the Indian-born head of al-Qaeda in the Indian Subcontinent claimed responsibility for a string attacks in Bangladesh and Pakistan, including Roy's.

The murder of Roy, an atheist who published a popular and provocative blog, marks an escalation by Islamist militants for control of Bangladesh. Religious fundamentalists are competing daily with secular government officials for power in the majority-Muslim country, one of the world's largest and poorest democracies.

In her first extensive interview since the attack, Ahmed criticized the Bangladeshi government for not responding more aggressively to her husband's slaying.

"This was well planned, choreographed - a global act of terrorism," she said. "But what almost bothers me more is that no one from the Bangladesh government has reached out to me. It's as if I don't exist, and they are afraid of the extremists. Is Bangladesh going to be the next Pakistan or Afghanistan?"

"WALKING A FINE LINE"

In an interview, Sajeeb Wazed, the son of Bangladesh Prime Minister Sheikh Hasina, said his mother offered private condolences to Roy's father. But the political situation in Bangladesh is too volatile for her to comment publicly, he said. Roy was an avowed atheist; the book he was promoting when he was killed is titled "The Virus of Faith."

"We are walking a fine line here," said Wazed, an informal consultant for the ruling party, the Awami League. "We don't want to be seen as atheists. It doesn't change our core beliefs. We believe in secularism," he said. "But given that our opposition party plays that religion card against us relentlessly, we can't come out strongly for him. It's about perception, not about reality."

A spokesman at the Bangladesh Embassy in Washington said he did not know why no one from his government had yet to contact Ahmed, who, like her late husband, is a dual Bangladeshi-U.S. citizen.

"We are shocked at the killing of Avijit Roy and have taken all measures to find the culprits responsible for this heinous act," said spokesman Shamim Ahmad. "Bangladesh is committed to fighting and ending extremism in all its forms."

The U.S. Federal Bureau of Investigation deployed agents to Dhaka and is working with Bangladesh authorities, an FBI spokeswoman said. Agents met most recently with Ahmed in the United States on Friday, Ahmed said.

Wazed said Roy's death came during a three-month period when 160 people died in bus bombings in Dhaka, and shortly before explosions near the prime minister's motorcade. Wazed blamed political opponents who, he said, seek to destabilize his mother's government.

"To us, Avijit Roy is no different than the 160 others that have been killed," he said. "We want to bring all the killers to justice. I understand why (his wife) is upset. My mother has been targeted by these same fundamentalists."

FREE THINKER

Well known in his native Bangladesh, Roy was largely anonymous in his suburban Atlanta neighborhood, where the couple lived since 2006.

By day, he worked as a Verizon software engineer. At night, he was a prolific writer, emerging as a leading critic of religious extremism in Bangladesh.

Roy, 43, wrote eight books and moderated a blog called Mukto-Mona (Free Thinker). To some, he was a provocative atheist, but his blog also reflected a strong belief in the value of civil debate, said his stepdaughter, Trisha Ahmed, 18.

"My dad was building a community of secularists who thought rationally," she said. "He wanted to start a conversation and see where it would go."

Roy was a young child during the formative years that followed Bangladesh's 1971 war of independence from Pakistan. The war had roots in colonialism and religion. Although Pakistan and Bangladesh shared neither a border nor common language, they had been joined as one in 1947, as the British departed the subcontinent. The demarcation was largely based on one factor: most who lived in Pakistan and Bangladesh were Muslim.

Bangladesh was founded as a secular country, but U.S. and Bangladesh officials said the Islamic fundamentalist influence began to increase in the 1990s as wealthy Arabs began building hundreds of religious schools. The same officials say militant influence also increased as waves of Bangladeshis who had moved to the Persian Gulf as laborers returned home with stricter Muslim views.

Roy's activism began around 2000, after he moved to Singapore for graduate school. He moderated a Yahoo email group and the blog followed, said Bangladeshi-British activist Rayan Rashid.

"It was a pioneering group, quite popular, long before Facebook and Twitter," said Rashid. "He was patient, witty, elegant and mature in dealing with dissidents. His goal was to win them over."

A THREAT

In 2002, while in Singapore, Roy noticed a blog post from a U.S. woman who wrote of religion, "I don't understand how people can believe in fairy tales." It was Rafida Ahmed, who would become his wife.

"A lot of people attacked me online for that post," she recalled. "I was a tech manager in Atlanta at the time, a single mom. I was intimidated and didn't respond. The next day, someone named Avijit Roy is defending me."

They dated long distance for years, and he reluctantly moved from Singapore to Atlanta in 2006: Ahmed would not leave the United States until her daughter completed high school. Roy held a doctorate in biomedical research, but found it easier to get a lucrative job and a U.S. visa as a software architect, his wife said.

After Trisha Ahmed was in college, the couple, by then married and U.S. citizens, decided to visit Dhaka. The two departed in mid-February.

"We knew that anything can happen in a country like that, and we took precautions," Ahmed said. "There was only one threat against him but we didn't take it seriously. Otherwise, we wouldn't have gone."

FINAL DAYS

Roy was a star attraction at the book fair. On a tranquil morning before his murder, he outlined a book he planned to write with Ahmed, and took her on a rickshaw tour of his childhood neighborhood. He exchanged Facebook messages with his stepdaughter, sharing in her excitement at attending a U.S. college lecture by the feminist Gloria Steinem.

"We were really, really happy," said Ahmed, who had edited her husband's books in Atlanta, but had not seen his influence first-hand in Bangladesh. "He had finally gotten to show me - in Bangladesh - how and why his work was so important."

Violence against secularists continues. On March 30, a Roy supporter, Washiqur Rahman, was hacked to death hacked in Dhaka by religious extremists.

After Roy's murder, a Dhaka man who had posted online threats was detained but not charged. Dhaka police have said they believe the Roy and Rahman murders were committed by the militant group Ansarullah Bangla Team.

"This looks much scarier than we originally thought," Ahmed said. (Edited by Michael Williams and Bill Tarrant)