China imposed the security law on Hong Kong just before midnight on June 30, punishing what Beijing broadly defines as subversion, secession, terrorism and collusion with foreign forces with up to life in prison.
*Lai, a millionaire publishing tycoon, has been a key critic of Beijing and widely believed to be a target of the new legislation.
*Mainland-born Lai was smuggled into Hong Kong on a fishing boat at the age of 12.
*He started working in a textile factory and by the age of 25, Lai had set up a successful garment business, manufacturing sweaters for major U.S. retailers.
*Lai says the June 4, 1989, crackdown on pro-democracy students in and around Tiananmen Square in Beijing spurred him to switch from the garment business to media.
*The tycoon had been a frequent visitor to Washington where he has met senior officials including Secretary of State Mike Pompeo to rally support for Hong Kong democracy, prompting Beijing to label him a "traitor".
*In an editorial in February, China's state-owned Global Times tabloid called Lai "a force of evil", rather than the "hero" of democracy painted by the West.
*The 71-year-old Lai owns Next Digital (0282.HK), which is considered one of the key remaining bastions of media freedom in Hong Kong. Next Digital owns Apple Daily, a popular tabloid known for its feisty and critical coverage of China and Hong Kong, and Lai is the publisher.
*Police raided Apple Daily's office building on Monday, going through documents and searching the newsroom, local television showed.
*Apple Daily has been hit by dwindling advertising revenues as well as frequent attacks by pro-Beijing voices in the city.
*In an interview with Reuters in May, Lai pledged to stay in Hong Kong and continue to fight for democracy even though he expected to be one of the targets of the new legislation.
"What I have, this place gave me, I will fight on till the last day. It will be (an) honour if I... sacrifice," Lai said.
*He has openly called on foreign countries to assist Hong Kong.
"The so-called foreign influence is our only salvation ... I think if the Americans support us very strongly, the other countries will follow through. America has to take the lead," he said in his comments in May.
*The pugnacious Lai, a thorn in the side of China, had already been arrested twice this year on illegal assembly charges, along with other leading activists, relating to anti-government protests last year.
*Lai, who founded casual wear brand Giordano in 1981, has seen his net worth slide from $1.2 billion in 2008, according to Forbes, to fall off the richest person list in the city. His net worth is now below $1 billion, but no precise estimates are available.
*Hong Kong police said on Monday they had arrested 7 people on suspicion of breaching the city's new national security law for offences including collusion with foreign powers. Police said the operation was still ongoing and further arrests possible.