A Department of Homeland Security official blame the death of a 32-year-old San Francisco woman on the city's sheriff's office for failing to honor a federal request to keep the alleged illegal immigrant shooter in custody.

The alleged shooter, Juan Francisco Lopez-Sanchez, had seven felonies on his record and was deported five times, but the San Francisco sheriff's office still decided to let him go even though DHS has requested that he be detained.

Philip Miller, a U.S. Immigration and Customs Enforcement official with DHS, testified before a Senate committee Tuesday that DHS had asked San Francisco to keep Sanchez detained, but that recent court cases have limited the federal government's ability to force communities to honor their requests to continue to hold criminals.

Miller's explanation came under intense questioning from Sen. Ron Johnson, a Wisconsin Republican who chairs the Homeland Security and Governmental Affairs Committee.

"Tell me why, specifically, when we have people illegally in this country and they have had seven prior felony convictions, why we're not able to deport these individuals?" Johnson asked.

"In this particular case, our detainer was not honored," Miller said.

"Who didn't honor it?" Johnson asked again.

"The San Francisco sheriff's department did not honor our detainer that we lodged," Miller replied.

Johnson then asked why ICE, or DHS has a whole, didn't have the legal authority to detain or apprehend Lopez-Sanchez and deport him.

Miller responded that he essentially fell through the bureaucratic cracks within federal and state laws – that the federal government was trying to pursue an outstanding felony narcotic warrant against him before deporting him.

"In that particular case, the gentleman had an outstanding felony narcotics warrant, and we feel strongly that the Bureau of Prisons made the right decision in trying to resolve that criminal warrant before we were allowed to take further civil action," he said.

Pressed on why ICE didn't pick him up after he served a federal sentence for illegal re-entry, Miller reiterated the DHS policy to "resolve all criminals warrants" before going forward with deportation. The answer seemed to only further infuriate Johnson.

"He was released in general society to create a murder – does that make any sense to you? Because I can tell you it doesn't make any sense to the American public and that's what we're trying to grapple with here," Johnson stormed.

Miller then sought to assure the Senate panel that DHS Secretary Jeh Johnson was trying to reach out to sanctuary cities that choose not to cooperate with federal detainer requests for illegal immigrants with criminal records to encourage them to comply.

"I think our secretary is taking very proactive steps through the priority enforcement program to try to bring a number of locations that aren't honoring the detention retainers" back into cooperating with the federal government, he said. "We hope to have communities like San Francisco come back and begin working with us proactively," he added.