According to ICE, more than 13,000 immigrants convicted of murder are living outside of immigration detention in the United States

More than 13,000 immigrants convicted of murder — either in the United States or abroad — are living outside Immigration and Customs Enforcement custody, according to data ICE submitted to Congress earlier this week.

The immigrants are part of ICE's “non-detained” list, meaning the agency has some information about the immigrants and has immigration cases pending in the U.S., but they are also not currently in custody because they are not a priority for immigration Three law enforcement officials said they are serving prison time because of their crimes or because ICE can't find them.

Two of the officials said it was unknown how many were detained because ICE is not always informed of data from state and local law enforcement agencies.

Acting ICE Director PJ Lechleitner submitted the data collected through July 21 as part of a March request from Republican Rep. Tony Gonzales of Texas.

A Department of Homeland Security spokesman said the data sent to Gonzales was misinterpreted and dated back four decades, long before the Biden administration.

It is not clear when the first of the 13,000 migrants arrived in the United States Two law enforcement officials familiar with the data told NBC News that many of the migrants on ICE's non-detained list, including serious criminals, entered the U.S. under previous administrations, including that of former President Donald Trump.

High numbers of non-detained immigrants with criminal convictions are nothing new, although they have increased in recent years.

A 2016 DHS Inspector General report found that there were 368,000 criminal immigrants who were not apprehended by ICE. According to ICE's fiscal year 2023 budget justification, as of June 5, 2021, nearly five months after Trump left office, there were 405,786 convicted criminal immigrants on the non-detained immigrant list, indicating that many violations occurred during the Trump administration became. As of July of this year, there were over 435,719 convicted criminal immigrants on ICE's non-detained list, according to data provided by ICE to Deputy Gonzales.

A DHS spokesperson told NBC News in a statement: “The data in this letter is being misinterpreted. The data goes back decades; “They include people who have entered the country in the last 40 years or more, and the vast majority of cases have been adjudicated over custody.” Long before this administration, they also include many who are under the jurisdiction of or currently under federal law enforcement -, state or local level.

During a campaign stop in Michigan on Friday, Trump used the data to criticize Vice President Kamala Harris for current immigration policies.

“I can finally look at it and say to the fake news, 'I told you so,'” Trump said. “These are tough, tough, vicious criminals who roam freely in our country.”

The White House has not yet commented on the data. An official told NBC News that the release of the data came as a surprise to the White House.

The 13,099 immigrants living in the U.S. who were convicted of murder may never have had contact with ICE, the two law enforcement officials said. Some may have crossed the border and then been released because the Border Patrol did not have information about their criminal history. In many cases, the United States is not informed of a person's criminal conviction until after they enter the country.

In other cases, migrants convicted of crimes can be released by state and local officials after serving their sentences without notifying ICE, as is common practice in many sanctuary cities. ICE must then locate the person after their release in order to arrest and deport them.

The two law enforcement officials said ICE is giving arrest priority to migrants convicted of serious crimes, such as murder.

However, the agency's limited resources limit how many people it can locate and arrest. Currently, more than 7.5 million immigrants are on ICE's “non-detained” immigrant list, meaning they have pending immigration cases but are not currently in custody.

Lechleitner told NBC News that more local jurisdictions are cooperating and beginning to rethink their sanctuary policies amid increasing attention to crimes committed by migrants.

NBC News joined ICE agents in Maryland earlier this year as they arrested a man convicted of murder in Colombia and a man convicted of attempted murder in El Salvador.

Agents said finding convicted criminals who are at large requires a tremendous amount of work, from search to arrest.