A former foreign service officer who worked in several capacities in the US Refugee Admissions Program around the world speaks from first hand experience when she says it is past time—way past time—for Congress to investigate the program.
After outlining examples of fraud that have been identified, Mary Doetsch says this at the Daily Caller:

It’s Time For Congress To Restore The Integrity Of The US Refugee Program

Perhaps even more disturbing than the actual fraud is the fact that this type of investigation is the exception rather than the norm. For decades, little heed has been paid to program’s extensive fraud.

As a former refugee coordinator who served throughout the Middle East, Africa, Russia and Cuba, I saw first-hand the flagrant abuses and scams that permeate the refugee program. I witnessed widespread exploitation and misuse, from identity fraud to marriage and family relation scams, and from private individuals profiting from their involvement in USRAP to distortion of the actual refugee definition to ensure greater numbers of people who are really migrants are admitted as refugees.

During my own time working in this program, I watched USRAP continue to expand unchecked, seemingly without concern for whether it served the best interests of its own citizens or the country.

While refugee admissions have been declining under the Trump administration, there has been almost no focus on programmatic fraud. Midway into the 2018 fiscal year, just over a quarter of the 45,000 individuals proposed in the FY18 refugee ceiling had entered the country. This slow-down in admissions may reduce some fraud, but without structural reform, it cannot be eliminated.

Too many government officials, often under the guise of humanitarianism, have continued to disregard both the external “pay-to-play bribery schemes” of the UN along with the internal fraud within USRAP operations. The once admirable refugee program has lost its integrity and must be reformed. The USRAP is in need of a complete overhaul and it’s time for Congress to take the lead.

Read it all here.
Good luck trying to get Congress to do anything.
See what Ms. Doetsch said back in February 2017 in response to Trump’s announcement of restrictions to refugee resettlement from certain countries.
This morning as I see CNN crowing about how Trey Gowdy says the FBI did no wrong in planting someone in the Trump campaign, I am reminded of how the chicken! (yes Gowdy!) never lifted a finger to try to get to the bottom of the problems with the USRAP when he was chairman of the subcommittee responsible for overseeing the program.