(CNN) -- Police said Friday that they believe they've found a gun that matches the serial number of a weapon purchased by One Goh, the man charged with fatally shooting seven people Monday at Oikos University, a small school in Oakland, California.
The gun was found early Friday in a downtown waterway, though it will require further investigation to determine if it was used in the shooting, according to a police statement.
Goh has been ordered to be held without bail. He is charged with seven counts of murder with special circumstances and three counts of attempted murder.
His next court appearance is April 30.
At a news conference Wednesday, District Attorney Nancy E. O'Malley clarified that Goh voluntarily left Oikos last November and wasn't expelled as earlier reported.
Oikos is a small college in Oakland that caters primarily to the Korean-American Christian community.
Goh, 43, who is Korean-American, was upset because he "wanted some money back for tuition he had paid, and it is also clear that he focused on one particular administrator at the school who was not present at the school on Monday," the day of the shooting, O'Malley told reporters.
Authorities have identified the seven people who were killed. The victims, all from California, were: Katleen Ping, 24; Judith Ona Seymour, 53, of San Jose; Lydia H. Sim, 21, of Hayward; Sonam Choedon, 33, of El Cerrito; Grace Eunhea Kim, 23, of Union City; Doris Ifeyinwa Chibuko, 40, of San Leandro; and Tshering Rinzing Bhutia, 38, of San Francisco, according to prosecutors.
Goh allegedly used a .45-caliber gun with four fully loaded ammunition magazines.