In this file photo taken on August 5, 2015, U.S. President Barack Obama speaks at American University in Washington, DC, August 5, 2015, about the nuclear deal reached with Iran. (Xinhua/AFP PHOTO)

LOS ANGELES, Dec. 20 (Xinhua) -- A 40-year-old inmate in federal prison in the U.S. state of Arizona has been sentenced to 48 months for making threats against former U.S. President Barack Obama.

Roger Dale Godwin, had previously pleaded guilty to making threats against Obama and mailing threatening communications, according to a press release from the Office of the United States Attorney, District of Arizona Wednesday.

In June 2016, while an inmate at Tucson's federal prison, Godwin sent out several letters addressed to then-President Obama and former Attorney General Loretta Lynch, threatening to injure or kill them.

Godwin must serve his four years consecutive to a 2014 sentence he is separately serving for mailing threats to judges and law enforcement while an inmate in the Wisconsin Department of Corrections, the release said.

In a separate incident, a 39-year-old man also living in Arizona was sentence on Monday to 37 months in federal prison for threatening to kill U.S. President Donald Trump.

Both cases were conducted by the Federal Bureau of Investigation.