The Chicago Police Memorial Foundation is now offering $20,000 to anyone who helps identify those responsible for fatally shooting Officer Clifton Lewis during a convenience store robbery a week ago, according to the foundation.

"These donors join us in our grief for Officer Lewis and his family," said Philip Cline, the foundation's executive director. "They also share our desire to do whatever is necessary to identify the person or persons responsible for taking the life of a fine Chicago Police officer."

Memorial services are scheduled for Thursday for Officer Lewis.

The foundation added $10,000 to the reward fund in addition to the $10,000 pledged last week. The latest donations came from the law firm of Andrew M. Hale and Associates and an anonymous donor. Each gave $5,000.

"Officer Lewis, one of the firm's clients, proudly represented his department and his profession in everything he did," said Andrew M. Hale. "It is important for his family, for police officers and for the entire community that these killers are brought to justice. We are hopeful that the reward will encourage anyone with information to come forward."

Officer Clifton Lewis, 41, was shot after two men robbed M & M Quick Foods on the west side on Dec. 29. He was working off-duty on a security detail.

In other news, the Chicago Police Memorial Foundation officials also provided a $50,000 check to the officer's family. Half of the contribution will go into a trust for Officer Lewis' 11-year old daughter.