Jed Carlos Lazaga was initially accused of throwing the grenade, based on information received by the Manila Police District (MPD) from an unnamed witness.

Anthony Leal Nepomuceno, NBI's prime suspect and an Alpha Phi Omega (APO) member, surrendered to Vice President of the Philippines Jejomar Binay on October 27.

[11] By 5:05 pm, a loud explosion occurred in the area where supporters for the San Beda College examinees were standing.

[12][17] The Manila Police District bomb squad rushed to the site of the blast and cordoned off the area to search the debris for parts of the explosive.

[15] We, legitimate fraternities based in major universities and colleges as well as communities nationwide, joins [sic] the Filipino nation in condemning in the strongest possible terms the brutal act of indiscriminate violence, which occurred during street revelry along Taft Avenue marking the end of this year’s bar examinations at the De La Salle University.

We denounce this gross display of brutality, which caused severe injury to innocent people and damage to property.

"[19] The incident was likewise condemned by San Beda Rector Aloysius Maranan,[20] Akbayan Youth Chairperson Marlon Cornelio, and Negros fraternities.

[21] Several members of six fraternities gathered at Quezon City on October 1 to participate in a candlelight vigil and express their sympathies.

[18] Renato Corona, Chief Justice of the Supreme Court, said in a statement that he had already ordered the Supreme Court security, the MPD, and the National Bureau of Investigation (NBI) to investigate the matter and "to identify the perpetrators of this senseless act of cowardice, and bring them to the bar of justice."

[23][24] On October 3, the Fraternal Order of Utopia from Ateneo de Manila University offered a ₱200,000 (US$4,620)[25]-reward to anyone who could present information identifying the perpetrator.

[11] MPD received from an unnamed witness, who was slightly injured by the blast, reports of a man in a black jacket and white shirt bearing the emblem of Alpha Kappa Rho.

This man allegedly threw the explosive from the other side of Taft Avenue, aiming for Tau Gamma Phi members; the throw fell short, hitting the San Beda students instead.

On the same day, NBI questioned Alpha Kappa Rho officials,[23] and expressed interest in summoning other fraternities that were present during the incident.

Del Rosario and his group presented pictures of Lazaga with at least 20 law students and professors of the university before the explosion.

Anthony Leal Nepomuceno, NBI's prime suspect, surrendered to Jejomar Binay, Vice President of the Philippines and an APO member, on October 27.

[34][35][36][37] At the time, Nepomuceno was a 26-year-old call center agent who graduated with a degree in information technology from Manuel L. Quezon University; he was also a member of APO.

This position was acknowledged by former Department of Justice (DOJ) Secretary Silvestre Bello III, who earlier pledged to help prosecute him if the evidence was strong.

[43] De Lima said that Nepomuceno matches the artist's sketch and the description given earlier, and the evidence against him is strong, as the NBI has at least 17 witnesses.

Police studied the possibility that the incident was linked to a fraternity rumble in December 2009, when Cromwell Dukha Jr. from APO was fatally stabbed, allegedly by Efraim Lim, a member of Tau Gamma Phi.

De Lima said that ongoing investigations on grenade-throwing incidents at La Consolacion College in 2008 and University of Perpetual Help System DALTA also suggest APO involvement.

[53][54] Raissa Laurel, a 23-year-old law student from San Sebastian College who lost both her legs due to the event, was given an award for her "courage and strength" by People Asia on its 11th anniversary on January 10.

[55] Meanwhile, Chief Justice Renato Corona of the Supreme Court pledged to personally administer Laurel's oath if she passes the bar.

[58] Laurel ran for city councilor of San Juan in the 2016 local elections, eventually winning a seat after placing third in her district.

[1][2][8][61] The 2011 exam was held in the University of Santo Tomas in November; DLSU ended its contract with the Supreme Court due to construction plans on the campus.