A Baldwin Park man known on the street as “Monster” and “Loony” has pleaded guilty to robbing two U.S. Postal Service mail carriers; he displayed a gun during the first robbery and used their stolen keys to raid apartment mailboxes across the area. Ruben Baca Lopez admitted to two counts of robbery of U.S. mail, money or other property by use of a dangerous weapon, along with one count of being a felon and prohibited person in possession of ammunition.
The first robbery happened in April 2024 in Baldwin Park, according to KTLA, when Baca Lopez approached a mail carrier sitting inside a USPS delivery truck and revealed a gun tucked in his waistband. He then took the carrier's smartphone, vehicle keys, keys providing access to apartment complexes, and a USPS-issued key, the station reports. According to the plea agreement, Baca Lopez used those stolen keys over the following weeks to access mailboxes and steal mail. Official notices from the U.S. Postal Inspection Service pinpoint the date of that first robbery as April 6, 2024.
A Second Robbery, Exactly One Month Later
A month later, Baca Lopez used a stolen apartment key to reach another USPS letter carrier, per the plea agreement described by the station. He forcibly took that carrier's cellphone, wallet, smartwatch, and USPS badge, along with two more USPS-issued keys. Postal Inspection Service notices place that second robbery on May 6, 2024 — precisely a month after the first, per the same law enforcement records.
After the robberies, the Postal Inspection Service issued an active federal arrest warrant for Baca Lopez and offered a reward of up to $50,000 for information leading to his capture, according to the notices. He has remained in federal custody since April 22, per the station's report.
Assault On Inspectors, Ghost Gun Recovered
Baca Lopez assaulted two Postal Inspection Service inspectors during their attempt to arrest him, and one inspector was injured during the confrontation, the station reports. At the time, he was carrying ammunition loaded in the chamber and magazine of a privately manufactured ghost gun with no serial number — despite being legally prohibited from possessing ammunition due to prior felony convictions.
Baca Lopez was previously convicted of domestic violence and false imprisonment in 2020 and of an assault-related offense in 2021, the outlet notes. Department of Justice records reviewed separately show an earlier misdemeanor domestic violence conviction from Los Angeles Superior Court in February 2016, a detail that extends his documented criminal history in Los Angeles County beyond the felony counts cited in the federal case, according to the Department of Justice.
Baca Lopez entered his guilty plea, according to the Department of Justice. He now faces up to 25 years in federal prison on each robbery count and up to 15 years on the ammunition possession count. Sentencing is scheduled for December 16, 2026.
Part of a Wider Pattern Targeting Postal Workers
Baca Lopez's case fits into a documented statewide and national surge in attacks on mail carriers tied to theft of universal “arrow keys” used to open cluster mailboxes. In September 2025, the California Attorney General's Office announced 72 felony convictions arising from Operation Checks in the Mail, a joint law enforcement sweep targeting organized mail theft and bank fraud operations in Los Angeles and San Bernardino counties, according to the State of California Department of Justice.
Nationally, robberies of letter carriers surged 30% to 643 incidents in 2023, while armed robberies resulting in physical injuries doubled to 61 cases, per data reported by CBS News. In response, federal authorities launched Project Safe Delivery in May 2023, a joint USPS and Postal Inspection Service initiative that has produced 3,654 mail theft arrests and 545 letter carrier robbery arrests nationwide through March 31, 2026, according to National Mailboxes. To make stolen master keys obsolete, USPS has replaced more than 42,000 traditional postal arrow locks with electronic locks and deployed over 23,000 high-security blue collection boxes, the same outlet reports.
Under federal statute 18 U.S.C. § 2114, robbing a person holding lawful custody of U.S. mail carries an aggravated statutory maximum sentence of 25 years in federal prison when a dangerous weapon is used or a victim's life is put in jeopardy, according to Eisner Gorin LLP. That statute underpins the maximum penalties Baca Lopez now faces on each robbery count.
The Baldwin Park case echoes another recent Los Angeles-area prosecution: a 46-year-old Glendale man pleaded guilty in a case involving approximately 30 stolen vehicles and mail theft. The two cases separately involve postal theft, while the Glendale case also involved check fraud and identity theft.
