The son of the man accused of trying to assassinate Donald Trump at his Florida golf course Sunday said his father had traveled to Ukraine and volunteered to provide what the son described as “humanitarian” aid to troops defending the country from Russian forces that invaded in 2022.

A source with direct knowledge of the investigation confirmed to the Guardian that the suspect in Sunday’s case is 58-year-old Ryan Wesley Routh – though law enforcement has not officially named him and there was no immediate indication of a motive.

His son, Oran Routh, repeatedly said he had not been able to immediately speak to his father or get information about the accusations against him, so he did not want to talk on his behalf.

But he also described his father as passionate about the Ukraine cause.

“My dad went over there and saw people fucking fighting and dying,” the younger Routh said during a brief telephone call when asked about his father. “He … tried to make sure shit was cool, and shit was not cool.”

Referring to the former president, who days earlier at the presidential debate would not answer whether he wanted Ukraine to win its war against Russia, Oran Routh said: “Meanwhile, this guy’s sitting behind his fucking desk, not doing a goddamn thing.”

A review of posts on Twitter/X associated with an account under Ryan Routh’s name also show Ukraine was an important cause to him. Two posts on that account from August 2023 addressed Ukraine’s president, Volodymyr Zelenskiy. One said Routh was in Kyiv and wanted to create a tent city for foreigners in a local park in hopes that would prompt more people from abroad to “raise great support and equipment”.

The other suggested that Zelenskiy asked Congress to put all members of the American military on paid leave “so they can fight as civilians in Ukraine”.

A third post from December also expressed concern for Haiti, which has been dealing with violent civil unrest.

Trump invoked both Ukraine and Haiti in his recent debate with Kamala Harris, the Democratic nominee for the 5 November White House race.

With respect to the latter country, the Republican nominee would only say he wanted Ukraine’s war with Russia “to stop”. But he made it a point to avoid saying he wanted Ukraine to triumph, fueling concerns that a second Trump presidency could suspend US military support to those defending the country.

Asked what he would tell his father if he could speak to him, Oran Routh said: “I know the discourse isn’t working, but we still need to stick to the discourse.”

He then politely excused himself from the conversation to try to find out more information about his father’s arrest on Sunday.

In a separate interview with CNN on Sunday, Oran Routh also called Ryan “a loving and caring father” and an “honest hardworking man”.

“I don’t know what has happened in Florida, and I hope things have just been blown out of proportion, because from the little I’ve heard it doesn’t sound like the man I know to do anything crazy, much less violent,” he said.

Online records show a man with the same name and age as Ryan Routh is registered to vote in North Carolina and lists his party affiliation as Democrat. Those records show he last voted in North Carolina’s presidential primaries in March.

However, many on X noted how the political views espoused by the account under Routh’s name were not exclusively pro-Democrat. The account described voting for Trump in 2016 and expressed support for a White House ticket combining the unsuccessful Republican presidential primary contenders Vivek Ramaswamy and Nikki Haley.

The account’s most recent post was addressed to Harris, timed in between Trump’s failed 13 July assassination at a political rally in Pennsylvania and when she replaced Joe Biden at the top of the Democratic ticket after the president opted to halt his re-election campaign. The post said the vice-president and Biden should visit two spectators wounded and attend the funeral of a rally-goer slain at the shooting before the attacker was shot dead by a Secret Service sniper.

“Show the world what compassion and humanity is all about,” the post said.

Sunday’s suspect was reported to have put the muzzle of a rifle through a fence in a wooded area at Trump International golf club in West Palm Beach, Florida, on Sunday afternoon.

Trump was golfing there at the time. An agent spotted the rifle and fired, prompting the suspect to flee before he was arrested in a neighboring county.