July 31 (Reuters) - Billionaire investor Ken Griffin's Citadel Securities said on Monday it has hired Goldman Sachs' David Rusoff as its chief legal officer.

Rusoff, who spent more than two decades at Wall Street's premier investment bank, will start his new role at the market making firm early next year and will report to Chief Executive Officer Peng Zhao.

He joined Goldman in 2000, in the legal department's investment management practice group, and most recently served as the bank's general counsel of global banking and markets. Rusoff was named managing director in 2005 and partner in 2016.

Separately, Goldman's Deputy General Counsel David Thomas is also leaving the firm after a long stint that began in 2005, according to an internal memo seen by Reuters on Monday.

Thomas was also serving as the bank's general counsel of asset and wealth management. He was appointed managing director in 2009 and partner in 2016.

Thomas will be joining Griffin's hedge fund Citadel, where he will lead the trading and markets legal and compliance teams, according to a report in Bloomberg News, citing a spokesperson.

Citadel did not immediately respond to a Reuters request for comment on the report. (Reporting by Manya Saini in Bengaluru and Lananh Nguyen in New York; Editing by Pooja Desai)