[4] At the encouragement of his father, he entered the Philippine Military Academy (PMA), and graduated from the institution in 1987 as part of the Hinirang class.

(Each year since 1967, the PMA assigns the graduating batch a unique honorific as verbal representation of the collective aspirations of the class.

[5][6][7] Sinas told SunStar Cebu in an interview that he joined the academy due to pressure from his father – he was warned that if he did not get in, he would not be accepted back home.

[8] Prior to serving as Central Visayas police chief, Sinas served in the Police Regional Office 12 (PRO-12) as Deputy Regional Director for Administration and in Camp Crame as secretary to the Directorial Staff under the Office of the Chief Directorial Staff and later, director of the PNP Crime Laboratory.

[13] and formally assumed the position on October 16, vowing to tackle illegal drugs, bribery, and gambling in Metro Manila.

[17] Sinas launched a biometrics system for the NCRPO on December 2, 2019, for accurate attendance monitoring of the police office's personnel.

[25] On November 9, 2020, "NCRPO Fitness Team", a YouTube channel run by the National Capital Region Police office (NCRPO) where Sinas was stationed for almost a year in 2019–2020, uploaded a video featuring Sinas leading a four-minute workout routine to the Voltes V theme song.

A mañanita is a tradition in the Philippine police force where personnel greet their senior officers during the early morning for their birthdays.

[14] On May 20, President Rodrigo Duterte decided against dismissing Sinas or transferring him to another post, vouching for his character believing that he was not at fault for being "serenaded" during his birthday.

The PNP made the announcement on March 11, 2021[34] on the day of his visit to Oriental Mindoro to attend a ceremonial COVID-19 vaccination for the local police force.

[35] On July 18, 2020, Sinas and other armed NCRPO officials were accused of harassment by the Delos Santos family, with the incident being filmed by a CCTV camera and the footage going viral online.