SAN FRANCISCO » A defendant in a San Francisco racketeering case will take the stand at his trial as prosecutors accuse him of ordering the killing of a rival before taking over his organization in Chinatown.

Raymond “Shrimp Boy” Chow is a reformed criminal whose testimony will be the “main thrust” of the defense’s case, Chow’s attorney, Tony Serra, said during opening statements on Monday.

Prosecutor Waqar Hasib said during his opening statement that Chow was the center of a criminal network who ordered the “cold-blooded, gangland-style” 2006 murder of Allen Leung.

Serra countered Chow did not participate in any killings or other criminal activity detailed in the investigation that led to the conviction of former state Sen. Leland Yee on a racketeering charge.

“My client is not, and they will never show he is anything analogous to a godfather,” Serra said.

Chow was the focus of a lengthy investigation that included an FBI agent posing as a member of the mafia who plied his targets in Chinatown — one of San Francisco’s most popular tourist attractions — with fancy meals, liquor and cash. More than two dozen people were indicted last year as part of the probe.

Hasib said a co-defendant will testify that Chow ordered the killing of Leung, who was then head of a fraternal organization known as the Ghee Kung Tong, the prosecutor said.

Federal investigators say Chow took over the Ghee Kung Tong after having Leung killed.

“This case is about this group of people engaging in this pattern of criminal activity,” Hasib said. “But most importantly, this case is about the person who is at the center of that, around whom all of that criminal activity revolved, around whom all those people revolved.”

Serra said Chow’s co-defendants would say anything to get a lighter sentence.

Federal agents say one of Chow’s associates led investigators to Yee, who acknowledged as part of his plea deal that he accepted thousands of dollars in exchange for favors and discussed helping an undercover FBI agent buy automatic weapons from the Philippines.

Yee is scheduled to be sentenced in December and faces a maximum of 20 years in prison. Jackson pleaded guilty to the same racketeering charge as Yee and is also scheduled to be sentenced next month.

Judge Charles Breyer said Chow’s trial could last until February.